Space-Charge Field Assisted Electron Acceleration by Plasma Wave in Magnetic Plasma Channel

Abstract

When the duration of a laser pulse is comparable to the plasma wave period, a large-amplitude plasma wave can be driven by the laser. In the presence of a guiding magnetic field, the large-amplitude plasma wave of finite transverse extent and large phase velocity resonantly accelerates the electrons to a higher energy level. For a small laser spot size, the laser exerts an axial as well as the radial ponderomotive force on the electrons that creates a density depression on the laser axis. This electron-depleted channel also creates a radial electric field (ion space-charge field). The acceleration of electrons in this channel is investigated, where the effect of ion space-charge field is considered, by solving the single particle dynamical equations. This paper shows that the space charge field plays an important role in electron energy gain during acceleration by a plasma wave in a magnetic plasma channel. This paper may be crucial in understanding the dynamics of particle motion and improving the quality of accelerated electron beam in the laser wakefield accelerators.