Performance testing of a carbon fiber array cathode in a hard-tube MILO

Abstract

In this paper, a carbon fiber array cathode was constructed and the application in a hard-tube magnetically insulated transmission line oscillator (MILO) was investigated. The performance was compared with a traditionally used polymer velvet cathode in the same conditions, where applied electric power ranged from 9 GW to 28 GW and microwave with power level of several GW was the output. The MILO worked on single shot mode or repetitive mode at 5 Hz. For both cathodes, the central frequencies of output microwaves are in the L-band, and the pulse durations (full width at half maximum) range from 25 to 50 ns. Experimental results show that the pulse duration of output microwave of the carbon fiber array cathode is shorter than the velvet cathode, and the power conversion efficiency is also somewhat lower than the velvet cathode. Although the performance testing results show that this carbon fiber array cathode is somewhat not as good as the traditional velvet cathode in the present state, the reasons for the disadvantages of the carbon fiber array cathode have been analyzed and the corresponding solutions are presented to improve the performance of this cathode. If expected solutions are put into effect, this carbon fiber array cathode may be able to replace the velvet cathode.