Resonant Wave‐Particle Interaction in an Explosively Unstable Beam‐Plasma System II. Investigation of the Relaxation Behaviour of the Electron Beam

Abstract

Three typical saturation mechanisms of the explosive instability (EI) in a beam-plasma system are investigated. It is shown that the maximum values of the electric field strengths of the erplosively unstable plasma waves can be of the same order ns the maximum wave amplitude of the linearly unstablc waves. Some conclusions with regard to the role played by the EI in the evolution of a r e d beam-plasma system are presented. The relaxation of a strongly modulated electron beam by the explosive wave coupling mechanism is examined in an appendix. A qualitative interpretation of the diversity of the EI saturation mechanisms found in this investigntion is given. Features of the Electron Beam RelaxationThe numerical investigations of [ 13 (Fig. 1.3) illustrate that the solutions of our systeiii of equations are physically significant almost only in the parameter range 0 5 5 (P > 1). In this range, however, the system of equations (1.37)-(1.42) (i.e. (37) of (13 is denoted by (1.37)) simplifies and obtains the form