Regular Article

Stability properties of a thin relativistic beam propagation in a magnetized plasma

¹ Institute of Physics, University of Belgrade, Pregrevica 118, 11080 Belgrade (Zemun), Serbia
² State University of Novi Pazar, Vuka Karadžića bb, 36300 Novi Pazar, Serbia
³ Dipartimento di Fisica, Università di Napoli “Federico II” Complesso Universitario M.S. Angelo, Napoli, Italy
⁴ INFN Sezione di Napoli, Complesso Universitario di M.S. Angelo, Napoli, Italy
⁵ Texas A&M University at Qatar, 23874 Doha, Qatar
⁶ SPIN-CNR, Complesso Universitario di M.S. Angelo, Napoli, Italy

^a e-mail: dusan.jovanovic@ipb.ac.rs

Received: 22 August 2017
Received in final form: 20 December 2017
Published online: 1 June 2018

Abstract

A self-consistent nonlinear hydrodynamic theory is presented of the propagation of a long and thin relativistic electron beam through a plasma that is relatively strongly magnetized. Such situation is encountered when the gyro-frequency is comparable to the plasma frequency, i.e. |Ω_e| ~ ω_pe. In addition, it is assumed the plasma density is much bigger than that of the beam. In the regime when the solution propagates in the comoving frame with a velocity that is much smaller than the thermal speed, a nonlinear stationary beam structure is found in which the electron motion in the transverse direction is negligible and whose transverse localization comes from the nonlinearity associated with its 3-D adiabatic expansion. Conversely, when the parallel velocity of the structure is sufficiently large to prevent the heat convection along the magnetic field, a helicoidally shaped stationary solution is found that is governed by the transverse convective nonlinearity. The profile of such beam is determined from a nonlinear dispersion relation and depends on the transverse size of the beam and its pitch angle to the magnetic field.