Improvement of vacuum maintenance capability and output pulse limit in a hard-tube MILO with a carbon fiber array cathode

Abstract

This paper reports a great improvement of vacuum maintenance capability in a hard-tube magnetically insulated transmission line oscillator (MILO) by replacing traditional polymer velvet cathode with a low-outgassing carbon fiber array cathode. Based on this improvement, we tested and compared the output pulse limits of this hard-tube MILO with the two cathodes under the same conditions, without an external pumping system after base vacuum pressure was reached. Experimental results reveal that the acceptable pressure for MILO operation is about 1.7 Pa, which is about 100 times higher than the conventional vacuum level (~10−2 Pa). Moreover, the output pulse limit of this hard-tube MILO has been increased from 7 pluses with polymer velvet cathode to about 127 pulses with carbon fiber array cathode. This promotion in the output pulse limit will speed up the application process of MILO.