Plasma electron contribution to beam emittance growth from Coulomb collisions in plasma-based accelerators

Abstract

Coulomb collisions with background plasma can cause emittance growth in plasma accelerators. This paper extends the theory to consider collisions with not only motionless plasma ions but also plasma electrons with relativistic motion, based on the Frankel cross section. The theory is verified by particle-in-cell simulations with a Monte Carlo collision module. It is shown that the electron contribution has the same amount as that of ions in linear acceleration regime and may not be negligible in nonlinear regime depending on the plasma electron density and its relativistic bulk velocity.