Nonlinear Plasma Wave in Magnetized Plasmas

TL;DR

This paper models nonlinear plasma oscillations in magnetized plasmas, showing magnetic fields prevent cavity closure behind laser pulses and revealing characteristic electron oscillation patterns confirmed by simulations and experiments.

Contribution

It provides an analytical description of nonlinear plasma oscillations in magnetized conditions, highlighting magnetic effects on cavity formation and electron dynamics.

Findings

Magnetic field prevents cavity closure behind laser pulses.

Characteristic 'Four-Ray Star' pattern observed in electron oscillations.

Simulation results align with experimental observations.

Abstract

Nonlinear axisymmetric cylindrical plasma oscillations in magnetized collisionless plasmas are a model for the electron fluid collapse on the axis behind an ultrashort relativisically intense laser pulse exciting a plasma wake wave. We present an analytical description of the strongly nonlinear oscillations showing that the magnetic field prevents closing of the cavity formed behind the laser pulse. This effect is demonstrated with 3D PIC simulations of the laser-plasma interaction. An analysis of the betatron oscillations of fast electrons in the presence of the magnetic field reveals a characteristic "Four-Ray Star" pattern which has been observed in the image of the electron bunch in experiments [T. Hosokai, et al., Phys. Rev. Lett. 97, 075004 (2006)].