Change search
Refine search result
1 - 47 of 47
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Al-Adili, Ali
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Investigation of 234U(n,f) with a Frisch-grid ionization chamber2011Licentiate thesis, monograph (Other academic)
    Abstract [en]

    This work treats three topics. The main topic concerns neutron-induced fission of 234U. The main goal is to investigate the fission-fragments properties  as a function of the incident neutron energy. The study was carried out using a twin Frisch-grid ionization chamber. The first fluctuations on fragment properties are presented, in terms of strong angular anisotropy oscillation.

    The second part of the work treats the data-acquisition systems in use, particularly for neutron-induced fission experiments. Modern digital systems are studied and compared with the conventional analogue systems. It was shown that the digital systems are superior in drift stability, pile-up correction and extended the possibilities of offline analysis.

    The third part of the work concerns the Frisch-grid inefficiency. The Frisch grid was introduced in the chamber to remove the angular dependency from the induced charge. However, the shielding is not perfect and a correction is needed for the small angular dependency. Two contradicting methods have been presented in literature, one adding, and the second subtracting the angular-dependent part from the detected signal. An experiment with Cf(sf) was designed and performed to solve the pending ambiguity. The results support the additive model.

  • 2.
    Al-Adili, Ali
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hambsch, Franz-Josef
    EC-JRC, IRMM, Geel, Belgium.
    Oberstedt, Stephan
    EC-JRC, IRMM, Geel, Belgium.
    Pomp, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Zeynalov, Shakir
    JINR, Dubna, Russia.
    Comparison of digital and analogue data acquisition systems for nuclear spectroscopy2010In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 624, no 3, p. 684-690Article in journal (Refereed)
    Abstract [en]

    In the present investigation the performance of digital data acquisition (DA) and analogue data acquisition (AA) systems are compared in neutron-induced fission experiments. The DA results are practically identical to the AA results in terms of angular-, energy- and mass-resolution, and both compare very well with literature data. However, major advantages were found with the digital techniques. DA allows for a very efficient αparticle pile-up correction. This is important when considering the accurate measurement of fission-fragment characteristics of highly αactive actinide isotopes relevant for the safe operation of Generation IV reactors and the successful reduction of long-lived radioactive nuclear waste. In case of a strong αemitter, when applying the αparticle pile-up correction, the peak-to-valley ratio of the energy distribution was significantly improved. In addition, DA offers a very flexible expanded off-line analysis and reduces the number of electronic modules drastically, leading to an increased stability against electronic drifts when long measurement times are required.

  • 3.
    Andersson Sundén, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Neutron Spectrometry Techniques for Fusion Plasmas: Instrumentation and Performance2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Neutron are emitted from a deuterium plasma with energies around 2.5 MeV. The neutron spectrum is intimately related to the ion velocity distribution of the plasma. As a consequence, the analysis of neutron energy spectra can give information of the plasma rotation, the ion temperature, heating efficiency and fusion power.

    The upgraded magnetic proton recoil spectrometer (MPRu), based on the thin-foil technique, is installed at the tokamak JET. The upgrade of the spectrometer was done to allow for measurements of deuterium plasmas. This thesis describes the hardware, the data reduction scheme and the kind of fusion plasma parameters that can be estimated from the data of the MPRu. The MPRu data from 3rd harmonic ion cyclotron resonance and beam heating are studied.

    Other neutron spectrometer techniques are reviewed as well, in particular in the aspect of suitability for neutron emission spectrometry at ITER. Each spectrometer technique is evaluated using synthetic data which is obtained from standard scenarios of ITER. From this evaluation, we conclude that the thin-foil technique is the best technique to measure, e.g., the ion temperature in terms of time resolution.

  • 4.
    Andersson Sundén, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ballabio, Luigi
    Cecconello, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ericsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gatu Johnson, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gorini, Giuseppe
    Hellesen, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ognissanto, Flora
    Ronchi, Emanuele
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Tardocchi, Marco
    Weiszflog, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Evaluation of neutron spectrometer techniques for ITER using synthetic data2013In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 701, p. 17p. 62-71Article in journal (Refereed)
    Abstract [en]

    A neutron spectrometer at ITER is expected to provide estimates of plasma parameters such as ion temperature, Ti, fuel ion ratio, nt/nd, and Qthermal/Qtot, with 10-20% precision at a time resolution, Δt, of at least 100 ms. The present paper describes a method for evaluating different neutron spectroscopy techniques based on their instrumental response functions and synthetic measurement data. We include five different neutron spectrometric techniques with realistic response functions, based on simulations and measurements where available. The techniques are magnetic proton recoil, thin-foil proton recoil, gamma discriminating organic scintillator, diamond and time-of-flight. The reference position and line of sight of a high resolution neutron spectrometer on ITER are used in the study. ITER plasma conditions are simulated for realistic operating scenarios. The ITER conditions evaluated are beam and radio frequency heated and thermal deuterium-tritium plasmas. Results are given for each technique in terms of the estimated time resolution at which the parameter determination can be made within the required precision (here 10% for Ti and the relative intensities of NB and RF emission components). It is shown that under the assumptions made, the thin-foil techniques out-perform the other spectroscopy techniques in practically all measurement situations. For thermal conditions, the range of achieved Δt in the determination of Ti varies in time scales from ms (for the magnetic and thin-foil proton recoil) to s (for gamma discriminating organic scintillator).

  • 5.
    Andersson Sundén, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Cecconello, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ericsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Gatu Johnson, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Giacomelli, Luca
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Hellesen, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Hjalmarsson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Källne, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ronchi, Emanuelle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Sangaroon, Siriyaporn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Weiszflog, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Instrumentation for neutron emission spectrometry in use at JET2010In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 623, no 2, p. 681-685Article in journal (Refereed)
    Abstract [en]

    The present contribution discusses two neutron spectrometers: the time-of-flight spectrometer (TOFOR) and the magnetic proton recoil spectrometer (MPRu). TOFOR uses fast plastic scintillators equipped with digital time-stamping electronics to register the time of each eligible scintillation event. The time trace for each detector is acquired practically dead-time free. The detectors of the MPRu are of phoswich type and each detector is connected to a digital transient recorder card that stores the full waveform for an event. By using phoswich detectors, pulse-shape discrimination techniques can be applied offline to distinguish signal events from background. A future upgrade of TOFOR could be digital “hybrid” cards, which store correlated time and waveform information. This information can be used to decrease the background level in the ttof spectrum, thereby increasing the operating range.

  • 6.
    Andersson Sundén, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ericsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gatu Johnson, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Giacomelli, L
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hellesen, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hjalmarsson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ronchi, E
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Weiszflog, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Källne, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Gorini, G
    Univ Milano -Bicocca, Milano, Italy.
    Tardocchi, M
    Univ Milano -Bicocca, Milano, Italy.
    Combo, A
    IST, Portugal.
    Cruz, N
    Batista, A
    Pereira, R
    Fortuna, R
    Sousa, J
    Popovichev, S
    The thin-foil magnetic proton recoil neutron spectrometer MPRu at JET2009In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 610, no 3, p. 682-699Article in journal (Refereed)
    Abstract [en]

    Neutrons are produced in fusion energy experiments with both deuterium (D) and deuterium–tritium (DT) plasmas. Neutron spectroscopy is a valuable tool in the study of the underlying fuel ion populations. The magnetic proton recoil neutron spectrometer, originally installed at JET in 1996 for 14-MeV neutron measurements, has been upgraded, with the main aim of improving its signal-to-background ratio (S/B), making measurements of the 2.5-MeV neutron emission in D plasmas possible. The upgrade includes a new focal-plane detector, based on the phoswich technique and consequently less sensitive to background, and a new custom-designed digital data acquisition system based on transient recorder cards. Results from JET show that the upgraded MPRu can measure 2.5-MeV neutrons with S/B=5, an improvement by a factor of 50 compared with the original MPR. S/B of 2.8×104 in future DT experiments is estimated. The performance of the MPRu is exemplified with results from recent D plasma operations at JET, concerning both measurements with Ohmic, ion cyclotron resonance (ICRH) and neutral beam injection (NBI) plasma heating, as well as measurements of tritium burn-up neutrons. The upgraded instrument allows for 2.5-MeV neutron emission and deuterium ion temperature measurements in plasmas with low levels of tritium, a feature necessary for the ITER experiment.

  • 7.
    Ehrengren, Kajsa
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Large scale introduction of wind power in an electricity productionsystem: Estimated effects on the carbon dioxide emissions2010Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis considers the effect of a large scale wind power introduction into an electricity system and the focus has been on the carbon dioxide emissions. Two different systems were studied, the Swedish and the Danish electricity system. When studying the Swedish electricity system different scenarios were created to see what might happen with the CO2 emissions with an introduction of a large amount of wind power. The model that was used is based on parameters such as regulating power, transmission capacity, export possibility, and the electricity generation mixes in the Nordic countries. Given that the transmission capacity is good enough, the conclusion is that the carbon dioxide emissions will be reduced with a large scale introduction of wind power. In the Danish electricity system wind power is already introduced to a large extent. The main purpose here was to investigate the development of the CO2 emissions and if it is possible to decide the actual change in carbon dioxide emissions due to the large scale introduction of wind power. The conclusions to this part are that the CO2 emissions per kWh produced electricity have decreased since the electricity generation mix has changed but the total amount of CO2 emissions fluctuates depending on weather, in a dry year less hydro power from Norway and Sweden can be used and more electricity from the fossil fuelled CHPs are generated. It has not been possible to determine the influence of the wind power on the CO2 emissions.

  • 8.
    Ericsson, Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Pomp, S
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sjöstrand, H
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Traneus, E
    Comment on "Piezonuclear decay of thorium" [Phys. Lett. A 373 (2009) 1956]2009In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 373, no 41, p. 3795-3796Article in journal (Refereed)
  • 9.
    Ericsson, Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Pomp, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Traneus, E.
    Raysearch AB, Stockholm.
    Piezonuclear reactions - do they really exist?2010In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 374, no 5, p. 750-753Article in journal (Refereed)
    Abstract [en]

    In a number of recent articles in this journal F. Cardone and collaborators have claimed the observation of several striking nuclear phenomena which they attribute to "piezonuclear reactions". One such claim [F. Cardone, R. Mignani, A. Petrucci, Phys. Lett. A 373 (2009) 1956] is that subjecting a solution of 228Th to cavitation leads to a "transformation" of thorium nuclei that is 104 times faster than the normal nuclear decay for this isotope. In a "Comment" [G. Ericsson, S. Pomp, H. Sjöstrand, E. Traneus, Phys. Lett. A 373 (2009) 3795] to the thorium work, we have criticized the evidence provided for this claim. In a "Reply" [F. Cardone, R. Mignani, A. Petrucci, Phys. Lett. A 373 (2009) 3797] Cardone et al. answer only some minor points but avoid addressing the real issue. The information provided in their Reply displays a worrying lack of control of their experimental situation and the data they put forward as evidence for their claims. We point out several shortcomings and errors in the described experimental preparations, set-up and reporting, as well as in the data analysis. We conclude that the evidence presented by Cardone et al. is insufficient to justify their claims of accelerated thorium decay (by "piezonuclear reactions" or otherwise).

  • 10.
    Eriksson, Jacob
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Calculations of neutron energy spectra from fast ion reactions in tokamak fusion plasmas2010Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A MATLAB code for calculating neutron energy spectra from JET discharges was developed. The code uses the fuel ion distribution calculated by the computer code SELFO to generate the spectrum through a Monte-Carlo simulation. The calculated spectra were then compared against experimental results from the neutron spectrometer TOFOR. In the calculations, the exact orbits of the fuel ions are taken into account, in order to investigate what effects this has on the spectrum. The reason for this is that, for certain plasma heating scenarios, large populations of fast fuel ions are formed. These fast ions may have Larmor radii of the order of decimeters, which is comparable to the width of the sight line of TOFOR, and may therefore affect the recorded neutron spectrum. A JET discharge with both NBI and 3rd harmonic ICRF heating was analyzed. The results show that the details of the line of sight of the detector indeed affects the neutron spectrum. This effect is probably important for other diagnostics techniques, such as gamma-ray spectroscopy and neutral particle analysis, as well. Good agreement with TOFOR data is observed, but not for the exact same time slice of the discharge, which leaves some questions yet to be investigated.

  • 11.
    Frassinetti, L
    et al.
    Alfven lab, KTH, Stockholm, Sweden.
    Brunsell, R
    Alfven lab, KTH, Stockholm, Sweden.
    Cecconello, M
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Drake, R
    Alfven lab, KTH, Stockholm, Sweden.
    Heat transport modelling in EXTRAP T2R2009In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 49, no 2, p. 025002-Article in journal (Refereed)
    Abstract [en]

    A model to estimate the heat transport in the EXTRAP T2R reversed field pinch (RFP) is described. The model, based on experimental and theoretical results, divides the RFP electron heat diffusivity χ e into three regions, one in the plasma core, where χ e is assumed to be determined by the tearing modes, one located around the reversal radius, where χ e is assumed not dependent on the magnetic fluctuations and one in the extreme edge, where high χ e is assumed. The absolute values of the core and of the reversal χ e are determined by simulating the electron temperature and the soft x-ray and by comparing the simulated signals with the experimental ones. The model is used to estimate the heat diffusivity and the energy confinement time during the flat top of standard plasmas, of deep F plasmas and of plasmas obtained with the intelligent shell.

  • 12.
    Fridström, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Response of the Gamma TIP Detectorsin a Nuclear Boiling Water Reactor2010Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In order to monitor a nuclear boiling water reactor fixed and movable detectors are used, such as the neutron sensitive LPRM (Local Power Range Monitors) detectors and the gamma sensitive TIP (Traversing Incore Probe) detectors. These provide a mean to verify the predictions obtained from core simulators, which are used for planning and following up the reactor operation. The core simulators calculate e.g. the neutron flux and power distribution in the reactor core. The simulators can also simulate the response in the LPRM and TIP detectors. By comparing with measurements the accuracy of the core simulators can be quantified. The core simulators used in this work are PHOENIX4 and POLCA7. Because of the complexity of the calculations, each fuel assembly is divided axially into typically 25 nodes, which are more or less cubic with a side length of about 15 cm. Each axial segment is simulated using a 2D core simulator, in this work PHOENIX4, which provides data to the 3D code, in this case POLCA7, which in turn perform calculations for the whole core. The core simulators currently use both radial pin weights and axial node weights to calculate the gamma TIP detector signal. A need to bring forward new weight factors has now been identified because of the introduction of new fuel designs. Therefore, the gamma TIP detector response has been simulated using a Monte Carlo code called MCNPX for a modern fuel type, SVEA-96 Optima2, which is manufactured by Westinghouse. The new weights showed some significant differences compared to the old weights, which seem to overestimate the radial weight of the closest fuel pins and the axial weight of the node in front of the detector. The new weights were also implemented and tested in the core simulators, but no significant differences could be seen when comparing the simulated detector response using new and old weights to authentic TIP measurements.

  • 13.
    Gatu Johnson, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Fusion Plasma Observations at JET with the TOFOR Neutron Spectrometer: Instrumental Challenges and Physics Results2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The neutron spectrometer TOFOR was installed at JET in 2005 for high-rate observation of neutrons from reactions between two deuterium (D) ions. Neutron spectrometry as a fusion plasma diagnostic technique is invoked to obtain information about the velocity states of fusion fuel ions. Based on neutron spectrometry data, conclusions can be drawn on the efficiency of plasma heating schemes as well as optimization of fuel ion confinement. The quality of TOFOR analysis is found to depend on how well the instrument response function is known; discriminator threshold levels, detector time alignment and electronics broadening are identified as crucial issues.

    About 19 percent of the neutrons observed with TOFOR have scattered off the JET vessel wall or other structures in the line-of-sight before reaching the instrument, as established through simulations and measurements. A method has been developed to take these neutrons into account in the analysis. TOFOR measurements of fast deuterium distributions are seen to agree with distributions deduced from NPA data, obtained based on an entirely different principle. This serves as validation of the modeling and analysis.

    Extraordinary statistics in the TOFOR measurements from JET pulses heated with 3rd harmonic RF heating on D beams allow for study of instabilities using neutron emission spectrometry. At ITER, similar studies should be possible on a more regular basis due to higher neutron rates.

    Observations of neutrons from Be+3He reactions in the TOFOR spectrum from D plasmas heated with fundamental RF tuned to minority 3He raise the question of beryllium neutrons at JET after installation of the ITER-like wall, and at ITER, with beryllium as the plasma facing component. This is especially important for the first few years of ITER operation, where the machine will not yet have been certified as a nuclear facility and should be run in zero-activation mode.

  • 14.
    Gatu Johnson, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Cecconello, Marco
    Hellesen, Carl
    Andersson Sundén, Erik
    Conroy, Sean
    Ericsson, Göran
    Ronchi, Emanuele
    Weiszflog, Matthias
    Gorini, Giuseppe
    Physics Department, Milano-Bicocca University, and Instituto di Fisica del Plasma del CNR, Milan, Italy (EURATOM-ENEA-CNR Association).
    Tardocchi, Marco
    Cross-validation of JET fast deuterium results from TOFOR and NPA2009In: 36th EPS Conference on Plasma Physics, Sofia, June 29 - July 3, 2009 ECA Vol.33E, 2009, p. P-2.151-Conference paper (Other academic)
  • 15.
    Gatu Johnson, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Conroy, Sean
    Andersson Sundén, Erik
    Cecconello, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ericsson, Göran
    Hellesen, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gherendi, Mihaela
    Association EURATOM-MEdC, National Institute for Laser, Plasma and Radiation Physics, Bucharest, Romania.
    Hjalmarsson, Anders
    Murari, Andrea
    Consorzio RFX-Associazione EURATOM ENEA per la Fusione, I-35127 Padova, Italy.
    Popovichev, Sergei
    EURATOM/CCFE Association, Culham Science Centre, Abingdon, United Kingdom.
    Ronchi, Emanuele
    Weiszflog, Matthias
    Zoita, Liviu Vasile
    Association EURATOM-MEdC, National Institute for Laser, Plasma and Radiation Physics, Bucharest, Romania.
    Modeling and TOFOR measurements of scattered neutrons at JETManuscript (preprint) (Other academic)
    Abstract [en]

    In this paper, the scattered and direct neutron fluxes in the line-of-sight of the TOFOR neutron spectrometer at JET are simulated and the simulations compared with measurement results. The Monte Carlo code MCNPX is used in the simulations, with a vessel material composition obtained from the JET drawing office and neutron emission profiles calculated from TRANSP simulations of beam ion density profiles. The MCNPX simulations show that the material composition of the scattering wall has a large effect on the shape of the scattered neutron spectrum. Neutron source profile shapes as well as radial and vertical source displacements in the TOFOR line-of-sight are shown to only marginally affect the scatter, while having a larger impact on the direct neutron flux. A matrix of simulated scatter spectra for mono-energetic source neutrons is created which is folded with an approximation of the source spectrum for each JET pulse studied to obtain a scatter component for use in the data analysis. The scatter components thus obtained are shown to describe the measured data. It is also demonstrated that the scattered flux is approximately constant relative to the total neutron yield as measured with the JET fission chambers, while there is a larger spread in the direct flux, consistent with simulations. The simulated effect on the integrated scattered/direct ratio of an increase with movements outward along the radial direction and a drop at higher values of the vertical plasma position is also reproduced in the measurements. Finally, the quantitative agreement found in scatter/direct ratios between simulations (0.185±0.005) and measurements (0.187±0.050) serves as a solid benchmark of the MCNPX model used.

  • 16.
    Gatu Johnson, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Cecconello, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson Sundén, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ericsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gherendi, M
    Hellesen, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hjalmarsson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Murari, A
    Popovichev, S
    Ronchi, Emanuele
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Weiszflog, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Zoita, L
    JET-EFDA Contributors,
    Modelling and TOFOR measurements of scattered neutrons at JET2010In: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 52, no 8, p. 085002-Article in journal (Refereed)
    Abstract [en]

    In this paper, the scattered and direct neutron fluxes in the line of sight (LOS) of the TOFOR neutron spectrometer at JET are simulated and the simulations compared with measurement results. The Monte Carlo code MCNPX is used in the simulations, with a vessel material composition obtained from the JET drawing office and neutron emission profiles calculated from TRANSP simulations of beam ion density profiles. The MCNPX simulations show that the material composition of the scattering wall has a large effect on the shape of the scattered neutron spectrum. Neutron source profile shapes as well as radial and vertical source displacements in the TOFOR LOS are shown to only marginally affect the scatter, while having a larger impact on the direct neutron flux. A matrix of simulated scatter spectra for mono-energetic source neutrons is created which is folded with an approximation of the source spectrum for each JET pulse studied to obtain a scatter component for use in the data analysis. The scatter components thus obtained are shown to describe the measured data. It is also demonstrated that the scattered flux is approximately constant relative to the total neutron yield as measured with the JET fission chambers, while there is a larger spread in the direct flux, consistent with simulations. The simulated effect on the integrated scattered/direct ratio of an increase with movements outward along the radial direction and a drop at higher values of the vertical plasma position is also reproduced in the measurements. Finally, the quantitative agreement found in scatter/direct ratios between simulations (0.185 ± 0.005) and measurements (0.187 ± 0.050) serves as a solid benchmark of the MCNPX model used.

  • 17.
    Gatu Johnson, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hellesen, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson Sundén, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Cecconello, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ericsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gorini, Giuseppe
    Physics Department, Milano-Bicocca University, and Istituto di Fisica del Plasma del CNR, Milan, Italy (EURATOM-ENEA-CNR Association).
    Kiptily, Vasily
    Euratom / UKAEA Fusion Association, Culham Science Centre, Abingdon, United Kingdom.
    Nocente, Massimo
    Physics Department, Milano-Bicocca University, and Istituto di Fisica del Plasma del CNR, Milan, Italy (EURATOM-ENEA-CNR Association).
    Pinches, Simon
    Euratom / UKAEA Fusion Association, Culham Science Centre, Abingdon, United Kingdom.
    Ronchi, Emanuele
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sharapov, Sergei
    Euratom / UKAEA Fusion Association, Culham Science Centre, Abingdon, United Kingdom.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Tardocchi, Marco
    Physics Department, Milano-Bicocca University, and Istituto di Fisica del Plasma del CNR, Milan, Italy (EURATOM-ENEA-CNR Association).
    Weiszflog, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Neutron emission from beryllium reactions in JET deuterium plasmas with 3He minority2010In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 50, no 4, p. 045005-Article in journal (Refereed)
    Abstract [en]

    Recent fast ion studies at JET involve ion cyclotron resonance frequency (ICRF) heating tuned to minority He-3 in cold deuterium plasmas, with beryllium evaporation in the vessel prior to the session. During the experiments, the high-resolution neutron spectrometer TOFOR was used to study the energy spectrum of emitted neutrons. Neutrons of energies up to 10MeV, not consistent with the neutron energy spectrum expected from d(d,n)He-3 reactions, were observed. In this paper, we interpret these neutrons as a first-time observation of a Be-9(He-3, n)C-11 neutron spectrum in a tokamak plasma, a conclusion based on a consistent analysis of experimental data and Monte Carlo simulations. Be-9(a, n)C-12 and Be-9(p, n)B-9 reactions are also simulated for p and a fusion products from d(He-3, a) p reactions; these two-step processes are seen to contribute on a level of about 10% of the single-step process in Be-9(He-3, n) C-11. Contributions to the total neutron yield from the Be-9(3He, n)C-11 reaction are found to be in the range 13 +/- 3 to 57 +/- 5%. We demonstrate how TOFOR can be used to simultaneously (i) probe the deuterium distribution, providing reliable measurements of the bulk deuterium temperature, here in the range 3.2 +/- 0.4 to 6.3 +/- 1.0 keV and (ii) provide an estimate of the beryllium concentration (in the range 0.48 +/- 0.17 to 6.4 +/- 1.7% of n(e) assuming T-3He = 300 keV). The observation of Be-9 related neutrons is relevant in view of the upcoming installation of a beryllium-coated ITER-like wall on JET and for ITER itself. An important implication is possible neutron-induced activation of the ITER vessel during the low-activation phase with ICRF heating tuned to minority He-3 in hydrogen plasmas.

  • 18.
    Gatu Johnson, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hellesen, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson Sundén, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Cecconello, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ericsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gorini, Giuseppe
    Physics Department, Milano-Bicocca University, and Istituto di Fisica del Plasma del CNR, Milan, Italy (EURATOM-ENEA-CNR Association).
    Nocente, Massimo
    Physics Department, Milano-Bicocca University, and Istituto di Fisica del Plasma del CNR, Milan, Italy (EURATOM-ENEA-CNR Association).
    Ronchi, Emanuele
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Tardocchi, Marco
    Physics Department, Milano-Bicocca University, and Istituto di Fisica del Plasma del CNR, Milan, Italy (EURATOM-ENEA-CNR Association).
    Weiszflog, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Neutron emission levels during the ITER zero activation phase2010In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 50, no 8, p. 084020-Article in journal (Refereed)
    Abstract [en]

    In recent experiments at JET, a contribution to the neutron emission from reactions between beryllium and 3He, 4He and H has been identified. With the beryllium walled planned for ITER, this raises the question of possible neutron activation during the ITER zero activation phase. Here, we estimate the neutron emission rates for various heating scenarios foreseen for this ITER phase using Monte Carlo simulations. The emission is seen to be strongly dependent on the scenario chosen and the assumptions involved. We find that fundamental minority heating can contribute on the scale of low temperature deuterium plasmas, depending on minority concentration and ICRH power applied. Harmonic ICRH leads to production of tails that can give rise to significant neutron emission rates, while rates from hydrogen beams will be near zero. Better knowledge of the zero activation phase conditions, and more sophisticated ICRH codes, would be needed to give exact rate predictions. We conclude that rates from so-called zero activation plasmas will be significantly lower than expected for the DD or DT phases, but far from zero.

  • 19. Giacomelli, L.
    et al.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Belli, F.
    Gorini, G.
    Horton, L.
    Joffrin, E.
    Lerche, E.
    Murari, A.
    Popovichev, S.
    Riva, M.
    Syme, B.
    Neutron Emission Profiles and Energy Spectra Measurements at JET2014In: FUSION REACTOR DIAGNOSTICS, 2014, p. 113-116Conference paper (Refereed)
    Abstract [en]

    The joint European Torus (JET, Culham, UK) is the largest tokamak in the world. It is devoted to nuclear fusion experiments of magnetic confined Deuterium (D) or Deuterium-Tritium (DT) plasmas. JET has been upgraded over the years and recently it has also become a test facility of the components designed for ITER, the next step fusion machine under construction in Cadarache (France). JET makes use of many different diagnostics to measure the physical quantities of interest in plasma experiments. Concerning D or plasmas neutron production, various types of detectors are implemented to provide information upon the neutron total yield, emission profile and energy spectrum. The neutron emission profile emitted from the JET plasma poloidal section is reconstructed using the neutron camera (KN3). In 2010 KN3 was equipped with a new digital data acquisition system capable of high rate neutron measurements (<0.5 MCps). A similar instrument will be implemented on ITER and it is currently in its design phase. Various types of neutron spectrometers with different view lines are also operational on JET. One of them is a new compact spectrometer (KM12) based on organic liquid scintillating material which was installed in 2010 and implements a similar digital data acquisition system as for KN3. This article illustrates the measurement results of KN3 neutron emission profiles and KM 12 neutron energy spectra from the latest JET D experimental campaign C31.

  • 20.
    Giacomelli, L.
    et al.
    Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England; Univ Milano Bicocca, Dept Phys, Milan, Italy.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England.
    Belli, F.
    Assoc EURATOM ENEA Fus, Rome, Italy.
    Gorini, G.
    Univ Milano Bicocca, Dept Phys, Milan, Italy; Ist Fis Plasma Piero Caldirola, Milan, Italy.
    Joffrin, E.
    Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England.
    Kiptily, V.
    Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England.
    Lerche, E.
    Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England.
    Murari, A.
    Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England.
    Plyusnin, V. V.
    Assoc EURATOM IST, Inst Plasmas & Fusao Nucl, Lisbon, Portugal.
    Popovichev, S.
    Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England.
    Reux, C.
    CEA IRFM, Cadarache, France.
    Riva, M.
    Assoc EURATOM ENEA Fus, Rome, Italy.
    Syme, D. B.
    Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England.
    High rate measurements of the neutron camera and broadband neutron spectrometer at JET2015Conference paper (Refereed)
    Abstract [en]

    The Joint European Torus (JET, Culham, UK) is the largest tokamak in the world. JET has been upgraded over the years and recently it has also become a test facility of the components designed for ITER, the next step fusion machine under construction in Cadarache (France). At JET, the neutron emission profile of Deuterium (D) or Deuterium-Tritium (DT) plasmas is reconstructed using the neutron camera (KN3). In 2010 KN3 was equipped with a new digital data acquisition system (DAQ) based on Field Programmable Gated Array (FPGA). According to specifications, the DAQ is capable of high rate measurements up to 0.5 MCps. A new compact broadband spectrometer (KM12) based on BC501A organic liquid scintillating material was also installed in the same year and implements a similar DAQ as for KN3. This article illustrates the observations on the DAQ high count rate performance of both KN3 and KM12 in the latest JET D plasma experiments related to hybrid scenario and runaway electrons. For the latter, >1 MCps event rate was achieved with consequences on the behavior of the FPGA and on the reliability of the measurements.

  • 21.
    Hellesen, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Diagnosing Fuel Ions in Fusion Plasmas using Neutron Emission Spectroscopy2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Neutron emission spectra, measured with the time of flight spectrometer TOFOR, at the joint European torus (JET) are presented in this thesis. TOFOR has been in use since 2005, routinely measuring the neutron emission from JET plasmas.

    The work in the thesis mainly concerns the modeling of the signatures in the neutron spectrum that reveal different parts of the fuel ion distribution, such as the thermal bulk plasma as well as energetic ions from neutral beam and ion cyclotron heating. Parametric models of the signatures, using plasma parameters as input, are employed to generate trial neutron spectra. The parameters, such as the fuel ion temperature or the fast ion distribution function, are deduced by iteratively fitting the trial spectra to the measured data. Measurements with TOFOR have been made and the models were applied. The studies are mainly on neutrons from d(d, n)3 He reactions(DD), although the emission from reactions with the plasma impurity 9 Be and triton burn up is covered as well.

    This has allowed for detailed studies of e.g. the physics ICRF heating as well as the interactions between energetic ions and plasma instabilities, such as toroidal Alfvé Eigenmodes.

  • 22.
    Hellesen, Carl
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Albergante, M.
    Andersson Sundén, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ballabio, Luigi
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ericsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gatu Johnson, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Giacomelli, Luca
    Gorini, Giuseppe
    Hjalmarsson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Jenkins, I.
    Källne, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Ronchi, Emanuele
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Tardocchi, Marco
    Voitsekhovich, Irina
    Weiszflog, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Neutron spectroscopy measurements and modeling of neutral beam heating fast ion dynamics2010In: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 52, no 8, p. 085013-Article in journal (Refereed)
    Abstract [en]

    The energy spectrum of the neutron emission from beam-target reactions in fusion plasmas at the Joint European Torus (JET) has been investigated. Different beam energies as well as injection angles were used. Both measurements and simulations of the energy spectrum were done. The measurements were made with the time-of-flight spectrometer TOFOR. Simulations of the neutron spectrum were based on first-principle calculations of neutral beam deposition profiles and the fast ion slowing down in the plasma using the code NUBEAM, which is a module of the TRANSP package. The shape of the neutron energy spectrum was seen to vary significantly depending on the energy of the beams as well as the injection angle and the deposition profile in the plasma. Cross validations of the measured and modeled neutron energy spectra were made, showing a good agreement for all investigated scenarios.

  • 23.
    Hellesen, Carl
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gatu Johnson, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson Sundén, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ericsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Eriksson, Jacob
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gorini, Giuseppe
    Johnson, Thomas
    Kiptily, Vasily
    Pinches, Simon
    Sharapov, Sergei
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Nocente, Massimo
    Tardocchi, Marco
    Weiszflog, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Measurements of fast ions and their interactions with MHD activity using neutron emission spectroscopy2010In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 50, no 8, p. 084006-Article in journal (Refereed)
    Abstract [en]

    Ion cyclotron radio frequency (ICRF) heating can produce fast ion populations with energies reaching up to several megaelectronvolts. Here, we present unique measurements of fast ion distributions from an experiment with 3rd harmonic ICRF heating on deuterium beams using neutron emission spectroscopy (NES). From the experiment, very high DD neutron rates were observed, using only modest external heating powers. This was attributed to acceleration of deuterium beam ions to energies up to about 2-3 MeV, where the DD reactivity is on a par with that of the DT reaction. The high neutron rates allowed for observations of changes in the fast deuterium energy distribution on a time scale of 50 ms. Clear correlations were seen between fast deuterium ions in different energy ranges and magnetohydrodynamic activities, such as monster sawteeth and toroidal Alfven eigen modes (TAE). Specifically, NES data showed that the number of deuterons in the region between 1 and 1.5 MeV were decaying significantly during strong TAE activity, while ions with lower energies around 500 keV were not affected. This was attributed to resonances with the TAE modes.

  • 24.
    Hellesen, Carl
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gatu Johnson, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson Sundén, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ericsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ronchi, Emanuelle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Weiszflog, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gorini, Guissepe
    Tardocchi, Marco
    Johnson, Thomas
    Kiptily, Vasily
    Pinches, Simon
    Sharapov, Sergei
    Neutron emission generated by fast deuterons accelerated with ion cyclotron heating at JET2010In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 50, no 2, p. 022001-Article in journal (Refereed)
    Abstract [en]

    For the first time, the neutron emission from JET plasmas heated with combined deuterium neutral beam injection and third harmonic ion cyclotron radio frequency heating have been studied with neutron emission spectroscopy (NES). Very high DD neutron rates were observed with only modest external heating powers, which was attributed to acceleration of deuterium beam ions to energies of about 2-3 MeV, where the DD reactivity is on a par of that of the DT reaction. Fast deuterium energy distributions were derived from analysis of NES data and confirm acceleration of deuterium beam ions up to energies around 3 MeV, in agreement with theoretical predictions. The high neutron rates allowed for observations of changes in the fast deuterium populations on a time scale of 50 ms. Correlations were seen between fast deuterium ions at different energies and magnetohydrodynamic activities, such as monster sawtooth crashes and toroidal Alfvén eigenmodes.

  • 25. Kiptily, V. G.
    et al.
    Beaumont, P.
    Belli, F.
    Cecil, F. E.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Craciunescu, T.
    Garcia-Munoz, M.
    Curuia, M.
    Darrow, D.
    Ericsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Fernandes, A. M.
    Giacomelli, L.
    Gorini, G.
    Murari, A.
    Nocente, M.
    Pereira, R. C.
    von Thun, C. Perez
    Popovichev, S.
    Riva, M.
    Santala, M.
    Soare, S.
    Sousa, J.
    Syme, D. B.
    Tardocchi, M.
    Zoita, V. L.
    Chugunov, I. N.
    Gin, D. B.
    Khilkevich, E.
    Shevelev, A. E.
    Goloborod'ko, V.
    Sharapov, S. E.
    Voitsekhovitch, I.
    Yavorskij, V.
    Fusion Alpha-Particle Diagnostics for DT Experiments on the Joint European Torus2014In: FUSION REACTOR DIAGNOSTICS, 2014, p. 87-92Conference paper (Refereed)
    Abstract [en]

    JET equipped with ITER-like wall (a beryllium wall and a tungsten divertor) can provide auxiliary heating with power up to 35MW, producing a significant population of alpha-particles in DT operation. The direct measurements of alphas are very difficult and alpha-particle studies require a significant development of dedicated diagnostics. JET now has an excellent set of confined and lost fast particle diagnostics for measuring the alpha-particle source and its evolution in space and time, alpha-particle energy distribution, and alpha-particle losses. This paper describes how the above mentioned JET diagnostic systems could be used for alpha-particle measurements, and what options exist for keeping the essential alpha-particle diagnostics functioning well in the presence of intense DT neutron flux. Also, alpha-particle diagnostics for ITER are discussed.

  • 26. Kiptily, V. G.
    et al.
    von Thun, Perez
    Pinches, D
    Sharapov, E
    Borba, D
    Cecil, E
    Darrow, D
    Goloborod'ko, V
    Craciunescu, T
    Johnson, T
    Nabais, F
    Reich, M
    Salmi, A
    Yavorskij, V
    Cecconello, M
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gorini, G
    Lomas, P
    Murari, A
    Parail, V
    Popovichev, S
    Saibene, G
    Sartori, R
    Syme, B
    Tardocchi, M
    de Vries, P
    Zoita, V. L.
    Recent progress in fast ion studies on JET2009In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 49, no 6, p. 065030-Article in journal (Refereed)
    Abstract [en]

    This paper presents recent results on fast ion studies on JET. A set of diagnostics for both confined and lost fast ions was employed for investigating the response of fast ions to MHD modes and for studying their behaviour in plasmas with toroidal field ripple and in shear-reversed plasmas. A dependence of the losses on MHD mode amplitude was deduced from the experimental data. A study of various plasma scenarios has shown that a significant redistribution of the fast ions happens during changes in the profile of the safety factor from shear-reversed to monotonic. Significant changes in the losses of ICRH accelerated protons were found to be associated with L-H confinement transitions in plasmas. After an L-H transition, an abrupt decrease in the ICRH proton losses was observed. In plasmas with an internal transport barrier, the loss of ICRH accelerated ions was found to increase as the barrier forms. Further results concerning fast ion losses were obtained during JET experiments in which the magnitude of the TF ripple was varied. The ripple losses of fusion products appear similar to classical losses, and are in agreement with modelling.

  • 27. Kiptily, V.
    et al.
    Gorini, G.
    Univ. Milano-Bicocca, Milano, Italy.
    Tardocchi, M.
    Univ. Milano-Bicocca, Milano, Italy.
    de Vries, P. C.
    Cecil, E.
    Chugunov, N.
    Craciunescu, T.
    Gatu Johnson, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gin, D.
    Goloborod’ko, V.
    Hellesen, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Johnson, T.
    KTH, Stockholm.
    Kneupner, K.
    Murari, A.
    Nocente, M.
    Univ. Milano-Bicocca, Milano, Italy.
    Perelli, E.
    Pietropaolo, A.
    Pinches, D.
    Proverbio, I.
    Univ. Milano-Bicocca, Milano, Italy.
    Sanchez, G.
    Sharapov, E.
    Shevelev, E.
    Syme, B.
    Yavorskij, V.
    Zoita, L.
    Doppler broadening of gamma ray lines and fast ion distribution in JET plasmas2010In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 50, no 8, p. 084001-Article in journal (Refereed)
    Abstract [en]

    The Doppler broadening of individual γ-ray lines was measured with a high purity germanium detector in JET plasma experiments. High-resolution γ-ray spectrometry of nuclear reactions between energetic D, 3 He and 4 He ions accelerated by ion cyclotron resonance heating and main plasma impurities such as carbon and beryllium has been used. The nuclear reactions giving rise to γ-rays have been identified and an effective temperature of the heated ions has been obtained in JET discharges. This technique could be used for fast ion and fusion alpha-particle studies in ITER.

  • 28. Kren, F.
    et al.
    Bashkanov, M.
    Bogoslawsky, D.
    Calén, Hans
    Uppsala University, The Svedberg Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Nuclear Physics.
    Clement, H.
    Demiroers, L.
    Ekström, Curt
    Uppsala University, The Svedberg Laboratory.
    Fransson, K.
    Uppsala University, The Svedberg Laboratory.
    Greiff, J.
    Uppsala University, The Svedberg Laboratory.
    Gustafsson, L.
    Uppsala University, Disciplinary Domain of Science and Technology, Faculty of Science and Technology.
    Höistad, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Nuclear Physics.
    Ivanov, G.
    Jacewicz, Marek
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Nuclear Physics.
    Jiganov, E.
    Johansson, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Nuclear Physics.
    Khakimova, O.
    Keleta, S.
    Uppsala University.
    Koch, I.
    Uppsala University.
    Kullander, Sven
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Kupsc, Andrzej
    Uppsala University, The Svedberg Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Nuclear Physics.
    Marciniewski, Pawel
    Uppsala University, The Svedberg Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Nuclear Physics.
    Meier, R.
    Morosov, B.
    Pauly, C.
    Petrén, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Petukhov, Y.
    Povtorejko, A.
    Ruber, R. J. M. Y.
    Uppsala University, The Svedberg Laboratory.
    Schönning, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Nuclear Physics.
    Scobel, W.
    Skorodko, T.
    Shwartz, B.
    Stepaniak, J.
    Thörngren-Engblom, P.
    Uppsala University.
    Tikhomirov, V.
    Wagner, G. J.
    Wolke, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Nuclear Physics.
    Yamamoto, A.
    Zabierowski, J.
    Zlomanczuk, Jozef
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Nuclear Physics.
    Exclusive measurements of pp -> d pi(+)pi(0): Double-pionic fusion without ABC effect2010In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 684, no 2-3, p. 110-113Article in journal (Refereed)
    Abstract [en]

    Exclusive measurements of the reaction pp -> d pi(+)pi(0) have been carried out at T-p = 1.1 GeV at the CELSIUS storage ring using the WASA detector. The isovector pi(+)pi(0) channel exhibits no enhancement at low invariant pi pi masses, i.e. no ABC effect. Therefore this most basic isovector double-pionic fusion reaction qualifies as an ideal test case for the conventional t-channel Delta Delta excitation process. Indeed, the obtained differential distributions reveal the conventional t-channel Delta Delta mechanism as the appropriate reaction process, which also accounts for the observed energy dependence of the total cross section.

  • 29.
    Loberg, John
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Novel Diagnostics and Computational Methods of Neutron Fluxes in Boiling Water Reactors2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The focus in this thesis is to improve knowledge of the BWR related uncertainties void, channel bow, and control rods. The presence of void determines the moderation of neutrons in BWRs. A high void fraction is less efficient in moderating neutrons than a low one. As a consequence, the ratio of thermal to fast neutrons is dependent on the surrounding void fraction. In this thesis, calculations with 2D/3D codes corroborate this dependence, the void correlation, to be linear and very robust to changes in different reactor parameters. The void fraction could be predicted from the ratio of simultaneously measured reaction rates from thermal and fast neutron detectors over the whole core with an uncertainty of ±1.5%. The only parameter found disturbing the void correlation significantly is channel bow. However, since channel bow is the only phenomenon found biasing the void correlation, it is found that the void prediction methodology can be used to indicate channel bow with a sensitivity of 4% per mm bow. Consequently, large channel bows could easily be detected. Increased knowledge of void fractions and channel bow could increase both safety and economy of nuclear power production.

    This thesis also investigates how 2D/3D codes used in production perform in calculating detailed impact of control rods on pin powers and their ability to perform control rod depletion calculations in the reflector region. It is found that the axial resolution used in 3D nodal codes has very large impact on pin power gradients, i.e., using a standard nodal size of ~15 cm can cause underestimations of 50% in pin power gradients, which could lead to fuel damages. In addition, two methods for determining the neutron flux in the control rod when it is withdrawn from the core are presented. Both methods can be used in a 3D nodal code to reproduce the neutron flux in the reflector region with an uncertainty of ±3%.

  • 30.
    Loberg, John
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Österlund, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Bejmer, Klaes-Håkan
    Blomgren, Jan
    A Method for Channel-Bow Indication by Neutron Flux Measurements2010Conference paper (Refereed)
  • 31.
    Loberg, John
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Österlund, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Bejmer, Klaes-Håkan
    Blomgren, Jan
    Kierkegaard, Jesper
    Investigation of Axial Power Gradients near an Unsymmetrical Control Blade TipIn: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100Article in journal (Refereed)
  • 32.
    Loberg, John
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Österlund, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Bejmer, Klaes-Håkan
    Blomgren, Jan
    Kierkegaard, Jesper
    Lindahl, Sten-Örjan
    Homogenization of Cross Sections and Computation of Discontinuity Factors for a Real 3D BWR Bottom Reflector for Comparison with Lattice and Nodal Codes2012In: Nuclear Technology, ISSN 0029-5450, E-ISSN 1943-7471, Vol. 177, no 1, p. 1-7Article in journal (Refereed)
    Abstract [en]

    Boiling water reactor (BWR) bottom reflector calculations in lattice codes such as CASMO are presently used only to produce accurate boundary conditions for core interfaces in nodal diffusion codes. Homogenized cross-section constants and discontinuity factors are calculated in one dimension (1-D) without the explicit presence of the control rod absorber. If the spatial flux in a BWR bottom reflector is required, for example, for depletion calculations of withdrawn control rods, the homogenization of the reflector must be based on a representation of the three-dimensional (3-D) geometry and material composition that is as true as possible. This paper investigates differences in cross-section and discontinuity factors from 1-D calculations in CASMO with 3-D Monte Carlo calculations of a realistic bottom reflector model in MCNP5. The cross-section and discontinuity factors from CASMO and MCNP5 are furthermore implemented in the nodal diffusion code SIMULATES to investigate the effect on the neutron fluxes in the bottom reflector. The results show that for the case investigated, the 1-D homogenization in CASMO5 produces a 26% overestimation of the homogenized thermal absorption cross section in the reflector and a 62% underestimation of the homogenized fast absorption cross section. These cross-section differences have essentially no impact on the neutron flux in the core but cause a 4.5% and 12.3% underestimation of the thermal and fast neutron flux, respectively, in the reflector region.

  • 33.
    Loberg, John
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Österlund, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Bejmer, Klaes-Håkan
    Blomgren, Jan
    Kierkegaard, Jesper
    Lindahl, Sten-Örjan
    Simulations and Models of Neutron Fluxes in BWRs Intended for Depletion Calculations of Withdrawn Control Rods2011In: Nuclear science and engineering, ISSN 0029-5639, E-ISSN 1943-748X, Vol. 177, no 3, p. 221-229Article in journal (Refereed)
    Abstract [en]

    Models of the neutron flux shape in a withdrawn control rod in a boiling water reactor (BWR) bottom reflector have been constructed from simulations with the Monte Carlo code MCNP. These neutron flux models are intended for determining absorber depletion and fast fluence accumulation for withdrawn control rods with nodal codes. So-called G-factors are created for coupling the neutron flux models to a conventional nodal code via the core bottom neutron flux. The neutron flux models and G-factors are created for three different neutron energies, and their dependence on various parameters such as blanket enrichments, Hf and B(4)C control rod absorber, and depletion and reflector geometry is investigated. The neutron flux models and G-factors are found to be very insensitive; the neutron flux models predict the simulated neutron flux in the withdrawn control rod from MCNP over a variety of reflector configurations with an error < 3.0%. This implies that the neutron flux models constructed in this paper are generally applicable for BWR reflectors and control rods not fundamentally deviating from the designs investigated in this paper.

  • 34.
    Loberg, John
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Österlund, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Blomgren, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Bejmer, Klaes-Håkan
    Neutron Detection-Based Void Monitoring in Boiling Water Reactors2010In: Nuclear science and engineering, ISSN 0029-5639, E-ISSN 1943-748X, Vol. 164, no 1, p. 69-79Article in journal (Refereed)
    Abstract [en]

    The ratio between the thermal- and fast-neutron fluxes in a boiling water reactor depends on the void fraction. The density of the steam-water mixture present in the core determines the efficiency of the moderation of fast neutrons born in fission; therefore, the void fraction could be determined by means of a simultaneous measurement of the thermal- and fast-neutron fluxes. Such measurement could also be used to investigate channel bow of the nuclear fuel bundles surrounding the detector because of sensitivity of the thermal flux to geometry changes. Calculations have been performed with both lattice and nodal codes to study the behavior of the void fraction correlation to the ratio of the thermal- and fast-neutron fluxes. The results prove the correlation to be nearly linear and robust. The rate of change of the correlation is insensitive to standard reactor operating parameters such as control rods and burnable absorbers; the sensitivity of the ratio to void fraction changes primarily depends on the geometry of the fuel bundles. A linear prediction model was used to represent the nodal code results. The absolute void fraction at over 792 positions in the core could be predicted with an absolute uncertainty of +/- 1.5%.

  • 35.
    Lundkvist, Niklas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    AMS on the actinides in spent nuclear fuel: a study on a technique for inventory measurements2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report is concerned with the question whether Accelerator mass spectrometry (AMS) is asuitable technique for measuring actinide inventory in spent nuclear fuel, and if it is better thanpresent techniques for these measurements. AMS is a kind of Mass spectrometry (MS) and has alot of applications where radio carbon dating is one of the most common. AMS has been used formaking measurements on actinides before but mostly from traces in bioassay that could have beenin contact with weapon plutonium, and in bioassay near enrichment plants and reprocessingplants. It is shown in this report that AMS is more sensitive in low level measurements than thecurrent technique for spent nuclear fuel. ICP-MS is the current technique in use for inventorymeasurements on nuclear fuel at Swedish Nuclear Fuel and Waste Management Company (SKB).ICP-MS is also a kind of MS technique which is well-tried for inventory measurements on spentnuclear fuel. The difference in sensitivity ranges in levels of magnitude depending on whichisotope that is interesting for measurements. The lower detection limits for AMS is about 105-107atoms which makes it possible to use samples from nuclear fuel that is in the order of 10-10-10-16gto achieve the lower detection limit. The recommendation from this report is to make studies ifAMS also is an economical and efficiently suitable technique for future use on the actinideinventory in spent nuclear fuel.

  • 36. Pochodzalla, Josef
    et al.
    Pomp, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Exploring the potential of antilambdas in nuclei with antiprotons2010In: International Journal of Modern Physics E, ISSN 0218-3013, Vol. 19, no 12, p. 2650-2655Article in journal (Refereed)
    Abstract [en]

    A schematic Monte Carlo simulation is used to examine the potential of exclusive hyperon-antihyperon pair production close to threshold in antiproton nucleus interactions to extract information on the interaction of antihyperons in nuclei. It is demonstrated that for Lambda(Lambda) over bar pairs produced at antiproton momenta of 1.66 GeV/c the asymmetry is sufficiently sensitive even if the density as well as the momentum dependencies of the potentials are considered. Data taken earlier by the PS185 Collaboration prove that these measurements are feasible.

  • 37. Ronchi, E.
    et al.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson Sundén, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ericsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gatu Johnson, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hellesen, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Weiszflog, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Applications of neural networks for free unfolding of experimental data from fusion neutron spectrometers2010In: International Journal of Nuclear Knowledge Management, Vol. 4, no 1, p. 25-31Article in journal (Refereed)
    Abstract [en]

    Free unfolding in neutron spectroscopy means reconstructing energy spectra from experimental data without a priori assumptions regarding their shape. Due to the ill-conditioned nature of the problem, this cannot be done analytically. Neural Networks (NNs) were applied to this task and synthetic data was used for training and testing. Results showed very consistent performance especially in the region of low and medium counts, where they fall near the Poisson statistical boundary. Comparison with other unfolding methods validated these results. Application time on the order of mus makes NNs suitable for real-time analysis. This approach can be applied to any instrument of which the response function is known.

  • 38.
    Ronchi, Emanuele
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson Sundén, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ericsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gatu Johnson, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Kallne, J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Hellesen, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hjalmarsson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Weiszflog, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Puccio, Walter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Åhlen, Lennart
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    A bipolar LED drive technique for high performance, stability and power in the nanosecond time scale2009In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 599, no 2-3, p. 243-247Article in journal (Refereed)
    Abstract [en]

    Pulsed light sources are often used to monitor the stability of light detectors such as photomultiplier tubes. Light emitting diodes (LEDs) are suitable for this due to their high specific light yield. While pulsed operation in the region of [mu]s is generally accessible with most LEDs and drivers, the ns time scale often represents a technical challenge. This paper describes a technique of bipolar LED drive that can produce light pulses of a few ns at high stability, reliability and power. The driver also offers control over the properties of the light pulse produced such as shape, intensity and repetition rate. This approach has been studied in 2003 and implemented in 2004 for two fusion neutron spectrometers at the Joint European Torus (JET) namely the Magnetic Proton Recoil upgrade (MPRu) and the Time Of Flight Optimized for Rate (TOFOR). A driver has been manufactured and connected to the scintillation detectors of each spectrometer through an optical fiber distribution network. Both MPRu and TOFOR have been successfully relying on this system for calibration and performance monitoring for several years, confirming the long-term stability and reliability of this technique.

  • 39.
    Ronchi, Emanuele
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson Sundén, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ericsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gatu Johnson, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hellesen, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Weiszflog, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    A parametric model for fusion neutron emissivity tomography for the KN3 neutron camera at JET2010In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 50, no 3, p. 035008-Article in journal (Refereed)
    Abstract [en]

    A parametric model for fusion neutron emissivity is presented and applied to the KN3 neutron camera data collected during the trace tritium experiment at the Joint European Torus. This work is aimed at achieving a good compromise between accuracy of tomographic reconstruction and low model complexity. This means low numerical degeneracy and good time consistency of the results. The model is compared both with plasma simulation codes and other tomographic techniques, which use KN3 line integrated emissivity data, showing good agreement over the entire data set analysed approximate to‰ˆ 500 plasma discharges).

  • 40.
    Ronchi, Emanuele
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson Sundén, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ericsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gatu Johnson, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hellesen, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Weiszflog, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Neural networks based neutron emissivity tomography at JET with real-time capabilities2010In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 613, no 2, p. 295-303Article in journal (Refereed)
    Abstract [en]

    Tomographic reconstruction techniques typically require computationally intensive algorithms which are not suitable for real-time application. This paper describes a framework to perform neutron emissivity tomography at the Joint European Torus (JET) using neural networks with successful results over a broad range of magnetic configurations, heating and fueling schemes. Application times in the [mu]s time scale allows for real-time applicability of the method.

  • 41.
    Simutkin, Vasily
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Fragment Mass Distributions in Neutron-Induced Fission of 232Th and 238U from 10 to 60 MeV2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Since its discovery, the phenomenon of nuclear fission is the object of extensive theoretical and experimental studies. However, we are still far from a complete understanding of the fission process. Nuclear theory can satisfactorily explain the process of neutron-induced fission at thermal neutron energies, but it meets problems at high neutron energies. However, new applications are nowadays developed involving neutron-induced fission in this energy domain. An example of such an application is accelerator-driven systems (ADS) which are dedicated to transmutation of highly radioactive nuclear waste. Conceptual studies of ADS require new nuclear data on neutron-induced reactions within a wide incident energy range. Along with structural, spallation target and other materials, data on neutron-induced fission are especially required for two nuclides, 232Th and 238U. At present, however, there are no published neutron-induced fission yield data for either 232Th or 238U at energies above 20 MeV.

    In this thesis, I present measurements of fission fragment mass yields at neutron energies from 10 to 60 MeV for 232Th and 238U. The experiment was done at the Louvain-la-Neuve quasi-monoenergetic neutron beam facility. A multi-section Frisch-gridded ionization chamber was used as the fission fragment detector. The fission fragment mass yields were measured at peak neutron energies of 33, 45, and 60 MeV. In addition, data for the neutron-energy intervals 9-11, 16-18, and 24-26 MeV were also extracted from the low-energy tail. The measurement results show that the symmetric fission component increases with incident neutron energy for both uranium and thorium, but it is more enhanced for thorium. The uranium results were compared to the only existing set of experimental data for neutron energies above 20 MeV. Reasonable agreement was found. However, our data show a lower symmetric fission component. For thorium, the present data are the first above 20 MeV.

    Model calculations with the TALYS code have also been done. This code is based on the multi-modal random neck-rupture model extended for higher excitation energies. We included a phenomenological model into the code and achieved a good description of our experimental results.

  • 42.
    Sjöstrand, Henrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson Sundén, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ericsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gatu Johnson, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Giacomelli, Luca
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gorini, Giuseppe
    Univ Milano -Bicocca, Milano, Italy.
    Hellesen, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hjalmarsson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Popovichev, Sergei
    Ronchi, Emanuelle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Tardocchi, Marco
    Univ Milano -Bicocca, Milano, Italy.
    Weiszflog, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gain stabilization control system of the upgraded magnetic protonrecoil neutron spectrometer at JET2009In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 80, no 6, p. 063505-Article in journal (Refereed)
    Abstract [en]

    Burning plasma experiments such as ITER and DEMO require diagnostics capable of withstanding the harsh environment generated by the intense neutron flux and to maintain stable operating conditions for times longer than present day systems. For these reasons, advanced control and monitoring (CM) systems will be necessary for the reliable operation of diagnostics. This paper describes the CM system of the upgraded magnetic proton recoil neutron spectrometer installed at the Joint European Torus focusing in particular on a technique for the stabilization of the gain of the photomultipliers coupled to the neutron detectors. The results presented here show that this technique provides good results over long time scales. The technique is of general interest for all diagnostics that employ scintillators coupled to photomultiplier tubes.

  • 43.
    Testa, D
    et al.
    CRPP, EDFL, Lausanne, Schweiz.
    Cecconello, M
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Schlatter, C
    CRPP, EDFL, Lausanne, Schweiz.
    contributors, JET-EFDA
    The dependence of the proton–triton thermo-nuclear fusion reaction rate on the temperature and total energy content of the high-energy proton distribution function2009In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 49, no 6, p. 062004-Article in journal (Refereed)
    Abstract [en]

    The endothermic nuclear reaction between thermal tritons and high-energy protons can represent an important contribution to the total neutron yield in tokamak plasmas heated by radio-frequency waves, as the first JET experiments have demonstrated (see Mantsinen et al 2001 Nucl. Fusion [/0029-5515/41/12/309] 41 1815 ). A further study based on more recent JET experiments was reported in Santala et al 2006 ( Plasma Phys. Control. Fusion [/0741-3335/48/8/012] 48 1233 ). In this letter we supplement and complete the previous analysis by reporting the first systematic measurement of the scaling of the proton–triton (pT) thermo-nuclear fusion reaction rate as a function of the total energy content and perpendicular tail temperature of the fast protons heated by radio-frequency waves. It is found that the pT-neutron rate increases almost linearly with the fast proton temperature and the total energy content.

  • 44. Tuboltsev, Yu. V.
    et al.
    Chichagov, Yu. V.
    Khilkevitch, E. M.
    Simutkin, V. D.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    A CAMAC-USB crate controller2010In: Instruments and experimental techniques (New York), ISSN 0020-4412, E-ISSN 1608-3180, Vol. 53, no 1, p. 79-83Article in journal (Refereed)
    Abstract [en]

    79-83A controller providing communication between a computer and a CAMAC crate via the USB bus is described. For this purpose, the controller includes a DLP-USB245M module, which allows a programmer to work with the controller through a virtual COM port and, at the same time, provides all the advantages of the USB standard. We consider versions of interactions of the DLP-USB module with controller registers on a programmable logic array and on the microcontroller.

  • 45. von Thun, C. Perez
    et al.
    Perona, A.
    Johnson, T.
    Sharapov, S. E.
    Reich, M.
    Kiptily, V. G.
    Cecconello, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Salmi, A.
    Goloborod’ko, V. Ya
    Pinches, S. D.
    García-Muñoz, M.
    Darrow, D.
    Brix, M.
    Voitsekhovitch, I.
    contributors, EFDA
    MeV-range fast ion losses induced by fishbones on JET2010In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 50, no 8, p. 084009-Article in journal (Refereed)
    Abstract [en]

    Energy and pitch angle resolved measurements of highly energetic (megaelectronvolt (MeV) range) suprathermal ions ejected from the plasma through interaction with fishbone oscillations are presented. The measurements are obtained with a 2D scintillator probe diagnostic installed on JET, which is designed to detect lost ions only above a certain energy threshold ( E min,D 200 keV). In the case reported here the lost ions are identified as fast protons which had been accelerated to high energies by ICRF minority heating. The energy of the lost protons ( 0.5–4 MeV) is approximately one order of magnitude higher than the energy of the injected beam ions (maximum 130 keV) driving the fishbone. Losses arriving at the probe are enhanced by about a factor 10–20 with respect to MHD-quiescent levels, and are found to increase quadratically with the fishbone amplitude. Using a number of simplifying assumptions, numerical simulations have been performed which combine the HAGIS, MISHKA and SELFO codes (where the distribution function predicted by SELFO has been validated against neutral particle analyser measurements). The losses are found to originate from orbit stochastic diffusion of trapped protons near the plasma boundary or from counter-passing protons deep in the plasma core, which transit under the influence of the fishbone into an unconfined trapped orbit. The simulations show further that the losses are of non-resonant type. The simulated energy and pitch angle distribution of the losses, the temporal behaviour of the losses during a fishbone cycle and the scaling of the losses with the fishbone amplitude are compared with experiment. The simulation results are mostly in broad agreement with experiment, but some of the predictions could not be reconciled with experiment using this model.

  • 46. Yavorskij, V.
    et al.
    Schoepf, K.
    Goloborod'ko, V.
    Cecconello, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Eriksson, L. -G
    Khan, M.
    Kiptily, V.
    Korotkov, A.
    Polevoi, A.
    Sharapov, S.
    Reznik, S.
    Results of Predictive Fokker-Planck Modelling of NBI Deuterons in ITER2011In: Journal of fusion energy, ISSN 0164-0313, E-ISSN 1572-9591, Vol. 30, no 4, p. 307-322Article in journal (Refereed)
    Abstract [en]

    First an analytical formalism is presented for calculating the source distribution of ions generated by neutral beam injection (NBI) in tokamak plasmas. A general NBI ion source term, applicable to studies in the phase space up to 6 dimensions, is provided for neutral beams with finite thickness and divergence. Further, using this source term for the envisaged NBI in ITER, we carry out 3D Fokker-Planck modelling of the steady-state deuteron distribution function of NBI produced fast deuterons relaxing on bulk plasma components. For two basic ITER scenarios we demonstrate the poloidal profiles of the beam deuteron density, of the NBI generated current as well as of the NBI power deposition to bulk electrons and ions. Further, we evaluate the capability of gamma and NPA diagnostics of NBI ions in ITER and demonstrate the sensitivity of the distributions of NBI generated ions to different ITER operation scenarios.

  • 47.
    Åberg Lindell, Matilda
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Safeguards Licensing Aspects of a Future Generation IV Demonstration Facility: A Case Study2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Generation IV (Gen IV) is a developing new generation of nuclear power reactors which is foreseen to bring about a safer and more sustainable production of nuclear power. A Swedish research program called GENIUS aims at developing the Gen IV technology, with emphasis on lead-cooled fast reactors. The present work is part of the GENIUS project, and deals with safeguards aspects for an envisioned future 100 MW Gen IV demonstration facility including storage and reprocessing plant. Also, the safeguards licensing aspects for the facilities have been investigated and results thereof are presented.

    As a basis for the study, the changed usage and handling of nuclear fuel, as compared to that of today, have been examined in order to determine how today's safeguards measures can be modified and extended to meet the needs of the demonstration facility. Safeguards approaches have been considered for within and between each unit at the demonstration facility, with the main focus on system aspects rather than proposing safeguards instrumentation on a detailed level.

    The proposed safeguards approach include the implementation of well-tried measures that are used at currently existing nuclear facilities as well as suggestions for new procedures. The former include, among others, regular inventory verifications, containment and surveillance measures as well as non-destructive and destructive measurements of nuclear materials. The traditional approaches may be improved and supplemented by modern techniques and approaches such as nuclear forensics, safeguards-by-design and improved on-line monitoring of streams of nuclear material. The safeguards approach for the demonstration facility should be outlined early in the licensing process, such that the facility units can be designed in a way that allows for implementation of adequate safeguards measures with minimal intrusion on the regular activities.

    For operating a nuclear facility in Sweden, two separate permits are required. A license application for a new facility shall be handed both to the Swedish Radiation Safety Authority and to the environmental court, which in parallel prepare for decisions according to the Nuclear Activities Act and the Environmental Code, respectively. In terms of the Swedish legislation, there are no fundamental differences between Gen IV facilities and currently existing plants. However, comprehensive investigations and evaluations would be required in order to license new Gen IV facilities.

1 - 47 of 47
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf