Diode polarity experiments on a coaxial vircator

A study on the interaction dynamics of a positively and negatively pulsed coaxial vircator is being performed at Texas Tech University. MAGIC, a 2.5D particle-in-cell code, is used to simulate the different geometries. The simulations performed indicate an increase in efficiency by approximately a factor of 2 for the negatively pulsed system compared to the positively pulsed system. Simulations are also performed to better understand the influencing factors of the systems. This paper describes the experimental results which are performed on a coaxial vircator with diode voltages from 400-500 kV at diode currents of 40-50 kA with pulse durations of /spl sim/50 nsec. Results that are given include microwave power, efficiency, spectral content and a possible explanation for the results.