Cathode in pulse magnetron for MW grade high power

Abstract

This paper introduced the diode test of a new type of oxide cathode of nickel sponge and the noticeable superiority when it was used for pulsed magnetron of 2.6MW. For the former, although common vacuum simulated diode with the space of 10mm between cathode and anode has simple structure ,the anode current of test diode was still measured up to 1.2A and 1.32A correspond to No.1 and No.2 new type of cathode. Otherwise, the pulsed emission current of the new type of cathode should be in range of 7.4 /spl sim/ 7.8A/cm/sup 2/for pulsed magnetron of 2.6MW high power. Three assembled pulsed magnetron of 2.6MW high power show that their output are more then 2.6MW specified value at Va=45 /spl sim/ 46KV and Ia=110A. In the condition of different duty cycle such as /spl tau/=4/spl mu/s f=122Hz and as /spl tau/=4/spl mu/s, f=250Hz, to measure beam meterage of complete machine with this magnetron show that current envelope is very good and operation is very stead. Beam meterage satisfies demand. In the case of specified operating status at Va=45KV and pulsed current 110A,beam meterage is up to 823Ld, more then the specified value of complete machine -700Ld and can satisfy applied need. Spectral shape is also satisfactory, which is monitored by means of AV4023B type of frequency spectrograph. The magnetron requires of heat load of the new type oxide cathode being very strict. So life test conducted carefully with 2.1MW magnetron first, 7 /spl sim/ 8 h a day, at /spl tau/=:2/spl mu/s, la=110A and P=2.1MW and continued 50 hours. During the whole operation, its performance and stabilization are perfect. The cathode has not obvious the phenomena of evaporation and sputter as well as virtual current. Later, life test conducted with No.2 tube, /spl tau/ 4/spl mu/s, Ia=110A and P=2.6MW, 7 /spl sim/ 8 hours a day and continued 23 hours 45 minutes. The test still keep on.