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Radial Drift Invariant in Long-Thin Mirrors
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
2012 (English)In: European Physical Journal D: Atomic, Molecular and Optical Physics, ISSN 1434-6060, E-ISSN 1434-6079, Vol. 66, no 28Article in journal (Refereed) Published
Abstract [en]

In omnigenous systems, guiding centers are constrained to move on magnetic surfaces. Sincea magnetic surface is determined by a constant radial Clebsch coordinate, omnigeneity implies that theguiding center radial coordinate (the Clebsch coordinate) is a constant of motion. Near omnigeneity isprobably a requirement for high quality confinement and in such systems only small oscillatory radialbanana guiding center excursions from the average drift surface occur. The guiding center radial coordinateis then the leading term for a more precise radial drift invariant Ir, corrected by oscillatory “bananaripple” terms. An analytical expression for the radial invariant is derived for long-thin quadrupolar mirrorequilibria. The formula for the invariant is then used in a Vlasov distribution function. Comparisons arefirst made with Vlasov equilibria using the adiabatic parallel invariant. To model radial density profiles, itis necessary to use the radial invariant (the parallel invariant is insufficient for this). The results are alsocompared with a fluid approach. In several aspects, the fluid and Vlasov system with the radial invariantgive analogous predictions. One difference is that the parallel current associated with finite banana widths could be derived from the radial invariant.

Place, publisher, year, edition, pages
Springer, 2012. Vol. 66, no 28
Keyword [en]
Radial invariant, quadrupolar mirror
National Category
Physical Sciences Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
URN: urn:nbn:se:uu:diva-183360DOI: 10.1140/epjd/e2011-20477-4ISI: 000300852900016OAI: diva2:562508
Available from: 2012-10-24 Created: 2012-10-24 Last updated: 2015-08-10Bibliographically approved
In thesis
1. Coil Design and Related Studies for the Fusion-Fission Reactor Concept SFLM Hybrid
Open this publication in new window or tab >>Coil Design and Related Studies for the Fusion-Fission Reactor Concept SFLM Hybrid
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A fusion-fission (hybrid) reactor is a combination of a fusion device and a subcritical fission reactor, where the fusion device acts as a neutron source and the power is mainly produced in the fission core. Hybrid reactors may be suitable for transmutation of transuranic isotopes in the spent nuclear fuel, due to the safety margin on criticality imposed by the subcritical fission core. The SFLM Hybrid project is a theoretical project that aims to point out the possibilities with steady-state mirror-based hybrid reactors. The quadrupolar magnetic mirror vacuum field is based on the Straight Field Line Mirror field and the central cell is 25 m long. A fission mantle surrounds the mirror cell. The fission to fusion power ratio is about 150 with keff = 0.97, implying that almost all the produced energy comes from fission. Beyond each mirror end magnetic expanders are located, which increase the plasma receiving “divertor” area and provide tolerable heat load on wall materials. The plasma is heated with ion cyclotron radio frequency heating and the fission mantle is cooled using a liquid lead-bismuth eutectic. The device is self-sufficient in tritium, and does not seem to suffer from severe material problems. A remaining issue may be the plasma electron temperature, which need to reach about 500 eV for efficient power production.  In this doctoral thesis, theoretical work has been done with the magnetic coil system of such a device and also with the overall concept. A new coil type, the fishbone coil, suitable for single cell quadrupolar mirrors, has been invented. Two vacuum field coil sets with satisfying properties have been found, where the most recent coil set consists of fishbone coils. Finite ß effects on the magnetic field have been investigated, showing that the flux tube ellipticity increases with ß. The ellipticity of the vacuum field increases slightly with radius, but with finite ß it decreases with radius. The maximum flux surface radial extensions decrease with ß, which is an unexpected and beneficial result. A radial invariant has also been identified, and particle simulations have been made to emphasize that quadrupolar mirrors must be symmetric or confinement may be lost.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. 138 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 991
Fusion, Fission, Hybrid reactor, Actinides, Mirror Machine, Quadrupolar mirror, Coils
National Category
Fusion, Plasma and Space Physics
Research subject
urn:nbn:se:uu:diva-183362 (URN)978-91-554-8521-4 (ISBN)
Public defence
2012-12-10, Polhemssalen, Ångströmslaboratoriet, Lägerhyddsv. 1, Uppsala, 10:15 (English)
Available from: 2012-11-19 Created: 2012-10-24 Last updated: 2013-01-23Bibliographically approved

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