INTERACTION OF A MODULATED ELECTRON BEAM WITH A MAGNETIZED PLASMA

Abstract. Experimental results concerning the interaction of a modulated electron beam with a magnetized plasma in the whistler frequency range are reported. It was shown experimentally that when a beam is injected into the plasma, waves can be generated by two possible mechanisms: Cherenkov emission of whistlers by the modulated beam, and transition radiation from the beam injection point. In the case of weak beam currents (nb/np<<10-4) the Cherenkov resonance radiation is more than an order of magnitude stronger than the transition radiation, the Cherenkov emission efficiency decreases at high beam currents. The transformation of the distribution function of the beam is investigated for the case of weak beam currents. It is shown that in the case of the Cherenkov interaction with whistlers the beam is retarded and the beam distribution function becomes wider and acquires a plateau region. The possibility of using modulated electron beams as an emitter of whistler-range waves has been discussed in recent years in application to active experiments in space. The theoretical works concerning this problem focus mainly on the analysis of the Cherenkov emission of electromagnetic waves in an infinite plasma and the first laboratory experiment demonstrate