Relativistic electron beam acceleration by nonlinear Landau damping of electrostatic waves in a magnetized plasma

Abstract

Acceleration and heating of a relativistic electron beam due to nonlinear electron Landau and cyclotron damping of electrostatic waves in a magnetized plasma are investigated theoretically and numerically on the basis of the relativistic kinetic wave and transport equations derived from the relativistic Vlasov–Maxwell equations. Two electrostatic waves interact nonlinearly with the relativistic electron beam satisfying the resonance condition for nonlinear electron Landau and cyclotron damping of ωk−ωk′−(k⊥−k⊥′)vd−(k∥−k∥′)vb≃mωce where vb and vd are the parallel and perpendicular velocities of the relativistic electron beam, respectively, and ωce is the relativistic electron cyclotron frequency. The beat waves produced by two electrostatic waves resonate with the relativistic electron beam. The relativistic transport equations using the relativistic drifted Maxwellian momentum distribution function of the relativistic electron beam were derived and analyzed. They show obviously its acceleration and heating (deceleration or cooling). Nonlinear electron Landau damping of the two lower-hybrid waves has been studied by the numerical analysis of relativistic nonlinear wave-particle coupling coefficients and it was clarified that the highly relativistic electron beam can be accelerated efficiently via the Compton scattering due to nonlinear electron Landau damping of the lower-hybrid waves.