Optimum angle for side injection of electrons into linear plasma wakefields

TL;DR

This paper develops a unified model to determine the optimal angle for side injection of electrons into linear plasma wakefields, balancing penetration and reflection to improve trapping efficiency.

Contribution

It introduces a comprehensive model for electron penetration and identifies the optimal injection angle for effective trapping in plasma wakefields.

Findings

Optimal injection angle minimizes electron reflection.

Electrons are separated into penetrated and reflected groups.

Reflection radius depends on electron energy.

Abstract

A unified model of electron penetration into linear plasma wakefields is formulated and studied. The optimum angle for side injection of electrons is found. At smaller angles, all electrons are reflected radially. At larger angles, electrons enter the wakefield with superfluous transverse momentum that is unfavorable for trapping. Separation of incident electrons into penetrated and reflected fractions occur in the outer region of the wakefield at some "reflection" radius that depends on the electron energy.