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Experimental studies on a coaxial vircator, designed for operation in TE11 mode
FOI.
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2011 (English)In: Proc. of Pulse Power Conference (PPC 2011), 2011, Vol. 38, no 1, 811-814 p.Conference paper, Published paper (Refereed)
Abstract [en]

Experiments on a coaxial vircator have been performed. A vircator is a narrow band high power microwave source without any external generated magnetic field [1]. A coaxial vircator is an advantageous design of a microwave radiation source for a compact HPM-system. With a limited size and outer diameter it is possible to use a larger emitting area compared to an axial design. A conventional coaxial vircator will generate the radiation in TM01 mode, due to its geometrical properties. For a compact HPM-system, radiation in TE11 mode is preferred when the radiated energy needs to be focused on a specific target. For operation in TE11 mode a sectioned emitter can be used rather than a circumcircular. The efficiency of the vircator can be greatly improved by optimizing the geometry of the vircator housing. The impedance of the pulsed power supply driving the vircator and the impedance of the vircator, depending on the A-K gap and amount of emitting material, is also important for maximizing the vircator efficiency. For the experiments reported on, the vircator was driven by a 500 kV/500 J compact Marx generator that can be operated repetitively at 10 Hz. For these experiments, the Marx generator was operating in single shot mode. During the experiments presented here, a couple of geometrical features were varied as well as the applied voltage. Their influence on the radiated field strength, dominating frequency and bandwidth are reported on and discussed.

Place, publisher, year, edition, pages
2011. Vol. 38, no 1, 811-814 p.
National Category
Fusion, Plasma and Space Physics
Identifiers
URN: urn:nbn:se:kth:diva-105121OAI: oai:DiVA.org:kth-105121DiVA: diva2:570069
Conference
Pulse Power Conference (PPC 2011)”, Chicago, USA, June 2011
Note

QC 20121116

Available from: 2012-11-16 Created: 2012-11-16 Last updated: 2012-11-22Bibliographically approved
In thesis
1. Design and Experiments with High Power Microwave Sources: The Virtual Cathode Oscillator
Open this publication in new window or tab >>Design and Experiments with High Power Microwave Sources: The Virtual Cathode Oscillator
2012 (English)Doctoral 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 simulations and 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 in this case the highest fields are generated. The vircator can be built in different geometries. Four different vircator types are investigated and the coaxial vircator is found to have advantages as a high radiated power and the possibility to vary the polarization during operation.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 and therefore 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, 2012. xx, 43 p.
Series
Trita-EE, ISSN 1653-5146 ; 2012:056
Keyword
High Power Microwaves Vircator
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-104794 (URN)978-91-7501-568-2 (ISBN)
Public defence
2012-12-14, F3, Lindstedtsvägen 26, KTH, Stockholm, 13:30 (English)
Opponent
Supervisors
Note

QC 20121122

Available from: 2012-11-22 Created: 2012-11-13 Last updated: 2012-11-22Bibliographically approved

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Elfsberg, MattiasHurtig, TomasMöller, Cecilia
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