A Study of Beam-Plasma Discharge. I. Wave Characteristics

Abstract

Strongly ionized, hot electron plasmas are produced by unmodulated, high power electron beam interaction with plasmas, of which properties have been investigated both experimentally and theoretically especially on characteristics of waves excited. When the plasma is considerably quiescent in a region of small beam power, low frequency ion plasma wave (∼several MHz) is found to be excited by a coupling with slow cyclotron wave of the electron beam. Besides this, in addition, weak excitation of high frequency oscillations (∼1 GHz) occurs in this region presumably due to a coupling between electron cyclotron wave of the plasma and slow cyclotron wave of the beam. In a turbulent plasma state above a certain critical beam power, on the one hand, plasma hybrid wave interaction with beam slow waves becomes essential for the plasma instability exciting powerful high frequency oscillations (∼several GHz), which seems to lead to production of strongly ionized plasmas.