Quasilinear interaction between Langmuir and Weibel turbulence in a beam-plasma system

Abstract

To analyze the joint development of two-stream and filamentation kinetic instabilities in a plasma with a particle beam, a quasilinear approach has been developed that accounts for the integral nonlinear interaction of modes arising from the variation of the spatially averaged velocity distribution function of the particles. On this basis, a numerical study has been carried out within the initial two-dimensional problem for a range of characteristic parameters of the plasma and the beam, focusing on the evolution of Langmuir (two-stream) and Weibel (filamentation) turbulence spectra. It has been established that the evolving Weibel-type magnetic turbulence can significantly reshape the region of the velocity distribution that is resonant with Langmuir waves, thereby strongly influencing the formation and particularly the damping of Langmuir turbulence. In turn, the Langmuir-type quasi-electrostatic turbulence can lead to substantial isotropization of the particle velocity distribution, thus altering the growth rates, evolution, and saturation levels of the Weibel turbulence modes.