Repetition rate operation of an improved magnetically insulated transmission line oscillator

In order to investigate the performances of repetition rate (rep-rate) operation of an improved magnetically insulated transmission line oscillator (MILO), a series of experiments are carried out on the improved MILO device, which is driven by 4 40 Omega, 50 ns rep-rate pulser, TORCH-01. Polymer velvet and graphite cathodes are tested, respectively, in the experiments, whose diameters and lengths are the same. The results of experimental comparison between them are presented in the paper. Both cathodes are tested at electric field strengths of about 300 kV/cm. The applied voltage has 60 ns duration with a rise time of 10 ns. This paper focuses on the performance of the voltage and current characteristics, the shot-to-shot reproducibility, the pressure evolution of the diode, and the lifetime of the cathodes, not upon the radiated microwave power. The experimental results show that the graphite cathode is superior to the velvet cathode in the lifetime and the shot-to-shot reproducibility during the rep-rate operation, and it is a promising cathode for the MILO device under the rep-rate conditions. (C) 2008 American Institute of Physics.