Simulation of the nonlinear evolution of large scale relativistic electron flow in dense plasmas

Abstract

A relativistic electron beam of about 100MA is transported through overdense plasmas in the fast ignition. The nonlinear dynamics of the relativistic electron beam in dense plasmas has been investigated using a two-dimensional fluid-particle hybrid (FPH) code [T. Taguchi et al., Phys. Rev. Lett. 86, 5055 (2001)] that combines a particle-in cell code with an Rational Cubic Interpolated Pseudo-Particle fluid code [F. Xiao et al., Comput. Phys. Commun. 93, 1 (1996)]. These simulations show that the relativistic electron beam breaks up into filaments from the Weibel instability and the filaments merge successively to larger filaments. When the relativistic electron beam diameter is large and the total current is over 100 times Alfvén limit current, many large scale filaments remain after the merging process and are confined in the initial beam diameter. It is found that the number of relativistic electron filaments decreases in proportion to t−0.9 in the fixed ion case and t−0.2 in the mobile ion case until ωpe0τ≈1000, respectively. This asymptotic behavior is caused by the random motion of filaments driven by fluctuating magnetic fields.