Vircator efficiency enhancement at plasma assistance

Abstract

Summary form only given. The experimental researches of generation of microwave radiation produced in a system of a relativistic electron beam (REB) with a supercritical current and external plasma source have been carried out. The pulsed electron accelerator has been put into operation that produces high-current relativistic electron beam with parameters: energy 280 keV, current 4.4 kA, pulse duration 0.8 msec. The generator of pulsed voltage supplied magnetically insolated diode of magnetron type by voltage impulse of 300 kV and duration 1 /spl mu/sec at diode impedance 64 Ohm. The diode was manufactured with cylindrical cathode from stainless steel of diameter 38 mm and emission edge width 0.1 mm. Anode has a conical form that transform into cylindrical liner of inner diameter 50 mm for transportation of tubular electron beam with diameter 32 mm and thickness 1 mm. Virtual cathode in magnetically insolated diode was realized by means of jump of the electrodynamics structure, namely sharp change of anode (drift tube) diameter from 40 mm, for which vacuum limiting current is 4.4 kA, to 50 mm, for which vacuum limiting current is 3.4 kA. The availability of the virtual cathode is confirmed by the measurements of input and output current of electron beam and also by registration of high-frequency radiation (vircator operation). The outer plasma was created by plasma source that consists of 4 plasma guns placed uniformly over azimuth of the drift tube for radial injection into virtual cathode region. The measured plasma parameters were: density 10/sup 12/ cm/sup -3/, temperature 3.6 eV, directed velocity 2.3/spl times/10/sup 6/ cm/sec. Microwave radiation was measured by detector /spl Lt/DK-J2M/spl Gt/ from the horn antenna. The results of investigations have shown that at presence of external plasma in electrodynamics' structure of the vircator-generator the power of microwave radiation is essentially increased in comparison to the vacuum case.