Excitation of an upper hybrid wave by Laguerre–Gaussian pulse in plasma with a density ramp and electron acceleration

Abstract

In this paper, the excitation of an upper hybrid wave (UHW) by propagation of a Laguerre–Gaussian (LG) laser pulse in an exponential density ramp plasma has been investigated in relativistic regime. A uniform static magnetic field was externally applied perpendicular to the propagation of the laser. The spatiotemporal dynamics of laser pulse have been studied by two coupled differential equations obtained via the moment theory approach. The propagating laser pulse excites an electron plasma wave, which further interacts with the laser pulse in the presence of applied transverse magnetic field and generates an UHW. The excited UHW further traps the plasma electrons and accelerates them. It has been observed that the presence of density ramp affects the laser dynamics, excited UHW, and electron acceleration. The applied magnetic field and modes of LG laser have also shown significant effect on electron acceleration. Energy gain of the order of 400 MeV/mm has been obtained for electrons.