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Nunnally W.,University of Missouri | McDonald K.,Science Engineering Solutions Inc
Proceedings of the 2010 IEEE International Power Modulator and High Voltage Conference, IPMHVC 2010 | Year: 2010

Semi-insulating Silicon Carbide (SiC) is a promising material for bulk, linear photoconductive switches due to the extremely large dielectric strength (3MV/cm), and a large band gap that has options for extrinsic photon closure, large thermal conductivity, and robust mechanical strength. Previous work has shown that the low mobility of SiC (as compared to GaAs) can provide similar conduction resistances with similar optical energies as a GaAs switch due to the large dielectric strength. The reported work documents the recent switching results with commercially available Vanadium compensated SiC substrates and low inductance, mechanical contacts. Presently available semi-insulating SiC is manufactured to serve as a substrate for Light Emitting Diodes due to the high thermal conductivity and the high electrical resistivity. The most efficient method of producing semi-insulating SiC is to compensate the background impurities with Vanadium to produce V:SiC. However, V:SIC is not the best material for photo-conductive switches as demonstrated by this work. This document reports on recent experiments employing commercially available Vanadium compensated SiC photo-conductive switch in a 10 Ohm Blumlein system at voltages up to 10 kV. The band structure of V:SiC is described along with the experimental approach and measurements of switch resistance and the effective recombination time. The experimental results also indicate that specially grown SiC materials with lower densities of Vanadium compensation can increase the performance of this system. © 2010 IEEE.

Schamiloglu E.,University of New Mexico | Brown D.,Sandia National Laboratories | McDonald K.F.,Science Engineering Solutions LLC
2011 30th URSI General Assembly and Scientific Symposium, URSIGASS 2011 | Year: 2011

This paper presents an approach to high power THz generation that uses a Switched Oscillator (SwO) as a photoconductively-switched antenna. A simplified model is used to demonstrate the SwO as an effective THz radiator. Numerical simulations are used to optimize various parameters of interest with the primary objective of maximizing the radiated energy and minimizing lossess. The radiation Q and resonant frequency are obtained as function of each parameter. © 2011 IEEE.

Clements K.R.,University of Missouri | Curry R.D.,University of Missouri | Druce R.,University of Missouri | Carter W.,University of Missouri | And 3 more authors.
IEEE Transactions on Dielectrics and Electrical Insulation | Year: 2013

To use two separate vircators simultaneously for two-frequency multipulse testing, we designed and constructed a versatile modulator which drives two vircators in parallel. We present details of the design, including vircator design with particle-in-cell simulations using CST Particle Studio® and MAGIC. The system operates as planned. Microwave output of the vircators under various operating conditions fits frequency varying inversely with the anode-cathode gap, although there is considerable scatter at larger gaps, likely due to cathode plasma non-uniformity. © 2012 IEEE.

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