Current filamentation instability of warm diluted electron beam in collisional weakly ionized plasma system

Abstract

Fluid description is employed to investigate the collisional current-filamentation instability (CFI) in a weakly ionized warm-beam/return current system, taking into account both thermal pressure and space charge effects. Describing the equilibrium configuration and using the local approximation method, the dispersion relation (DR) is obtained in the presence of binary collision terms between charged and neutral particles. Analyzing the obtained DR for a warm-beam cold-plasma system shows increment of thermal effects, consisting of collision and thermal pressure, by electron beam temperature and plasma ionization degree decreases the unstable wavelength region as well as the maximum growth rate of CFI, called thermal-driven stabilization. On the other hand, increasing the beam current density is toward the destabilization (called current-driven destabilization) by broadening the unstable wavelength region and increasing the maximum growth rate of CFI. One can deduce that competition between thermal-driven stabilization and current-driven destabilization determines the stability degree of weakly ionized systems.