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High Power Microwave Sources: design and experiments
KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

High-Power Microwaves (HPM) can be used to intentionally disturb or destroy electronic equipment at a distance by inducing high voltages and currents. This thesis presents results from experiments with a narrow band HPM source, the vircator. The high voltages needed to generate HPM puts the vircator under great stress, especially the electrode materials. Several electrode materials have been tested for endurance and their influence on the characteristics of the microwave pulse. With the proper materials the shot-to-shot variations are small and the geometry can be optimized in terms of e.g. output power or frequency content. Experiments with a resonant cavity added to the vircator geometry showed that with proper tuning of the cavity, the frequency content of the microwave radiation is very narrow banded and the highest radiated fields are registred. Since HPM pulses are very short and have high field strengths, special field probes are needed. An HPM pulse may shift in frequency during the pulse so it is very important to be able to compensate for the frequency dependence of the entire measurement system. The development and use of a far-field measurement system is described.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology , 2011. , xvi,33 p.
Series
Trita-EE, ISSN 1653-5146 ; 2011:046
National Category
Fusion, Plasma and Space Physics Fusion, Plasma and Space Physics
Identifiers
URN: urn:nbn:se:kth:diva-34072ISBN: 978-91-7501-044-1OAI: oai:DiVA.org:kth-34072DiVA: diva2:419001
Presentation
2011-06-10, Seminarierummet, avd för Rymd- och plasmafysik, KTH, Stockholm, 10:15
Opponent
Supervisors
Note
QC 20110616Available from: 2011-06-16 Created: 2011-05-25 Last updated: 2011-06-16Bibliographically approved
List of papers
1. Experimental Studies of Anode and Cathode Materials in a Repetitive Driven Axial Vircator
Open this publication in new window or tab >>Experimental Studies of Anode and Cathode Materials in a Repetitive Driven Axial Vircator
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2008 (English)In: IEEE Transactions on Plasma Science, ISSN 0093-3813, E-ISSN 1939-9375, Vol. 36, 688-693 p.Article in journal (Refereed) Published
Abstract [en]

 Repetitive use of a high-power microwave (HPM) radiation source implies strong erosion on cathode and anode materials. Electrode material endurance has been studied in a series of experiments with an axial vircator powered by a compact Marx generator. The Marx generator operated in a 10 Hz repetitive mode with a burst of ten pulses. Velvet and graphite was used as electron-emitting materials, and they showed markedly different pulse characteristics. Three different anode materials were used; stainless steel mesh, stainless steel wires and molybdenum wires, which all had different influence on the pulse characteristics.

Keyword
anodes, cathodes, high power microwaves, Marx generators, microwave devices, microwave generation, repetitive, vircator
National Category
Fusion, Plasma and Space Physics Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-33888 (URN)10.1109/TPS.2008.922222 (DOI)000256885800016 ()
Note
QC 20110616Available from: 2011-06-16 Created: 2011-05-23 Last updated: 2012-11-22Bibliographically approved
2. Magnetic field measurement system for HPM research
Open this publication in new window or tab >>Magnetic field measurement system for HPM research
2009 (English)In: Proc. of Radiovetenskap och kommunikation (RVK08), 2009, Vol. 1106, 86-93 p.Conference paper (Refereed)
Abstract [en]

One method to characterize the radiated microwave field from a high-power microwave (HPM) source is to measure the radiated high-level electromagnetic field in several locations at a high sampling rate registering the frequency time dependence, thus being able to determine the radiated pattern and mode. A complete free-field measurement system for measuring the magnetic field component in high-level electromagnetic fields has been developed at FOI. The system consists of a B-dot sensor and a balun, both designed and constructed at FOI. The B-dot sensor is designed as two cylindrical loop sensors with differential output. The balun is a microstrip design etched on a dual sided PTFE circuit board. Complete systems have been calibrated at SP Technical Research Institute of Sweden. A method to analyze the data from the free-field systems has been developed.

Series
, AIP Conference Proceedings, ISSN 0094-243X
National Category
Fusion, Plasma and Space Physics Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-34814 (URN)000264867300009 ()
Conference
RVK
Note
QC 20110616Available from: 2011-06-16 Created: 2011-06-16 Last updated: 2012-11-22Bibliographically approved
3. Experimental Studies of the Influence of a Resonance Cavity in an Axial Vircator
Open this publication in new window or tab >>Experimental Studies of the Influence of a Resonance Cavity in an Axial Vircator
2010 (English)In: IEEE Transactions on Plasma Science, ISSN 0093-3813, E-ISSN 1939-9375, Vol. 38, no 6, 1318-1324 p.Article in journal (Refereed) Published
Abstract [en]

Experiments on an axial virtual-cathode oscillator (vircator) with a resonance cavity enclosing the virtual cathode are reported. The vircator is driven by a repetitive Marx generator operating in a single-shot mode. To be able to separate different radiation mechanisms, the design of the vircator allows adjustment of the cavity depth as well as the way microwave radiation is extracted. The microwave radiation is measured with a pair of free-field B-dot sensors. The maximum field strengths were registered when the bandwidth was very narrow.

Keyword
axial virtual-cathode oscillator (vircator), high-power microwave, resonant cavity
National Category
Fusion, Plasma and Space Physics Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-34819 (URN)10.1109/TPS.2010.2042822 (DOI)000281764600023 ()
Note
QC 20110616Available from: 2011-06-16 Created: 2011-06-16 Last updated: 2012-11-22Bibliographically approved

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