Experimental Studies of Explosive Instability in an Electron Beam-Plasma System

Abstract

The explosive instability due to nonlinear wave-particle interaction has been observed experimentally. The slow space charge wave of the electron beam and the obliquely propagating electrostatic electron cyclotron harmonic wave interact nonlinearly with the electron beam and grow simultaneously, satisfying the resonant condition ω₁−ω₂−(k_⁄⁄1−k_⁄⁄2)v_b=ω_c. One wave is amplified exponentially by increasing the power of the other wave. The virtual wave has also been observed. The nonlinear wave-particle coupling coefficients are measured quantitatively from the spatial growth rate, and found to be in good agreement with theory.