Plasma Wakefield Accelerators with Ion Motion and the E-314 Experiment at FACET-II

TL;DR

This paper explores the complex physics of ion motion in plasma wakefield accelerators, discusses plans for the E-314 experiment at FACET-II to demonstrate this phenomenon, and presents simulation results relevant to the experiment.

Contribution

It provides a detailed analysis of ion motion effects in plasma accelerators and outlines experimental plans and simulation results for the E-314 experiment.

Findings

Ion motion causes nonlinear focusing fields in plasma accelerators.

Simulations show formation of a dense ion filament on the axis.

Careful beam matching can mitigate emittance growth.

Abstract

A future plasma based linear collider has the potential to reach unprecedented energies and transform our understanding of high energy physics. The extremely dense beams in such a device would cause the plasma ions to fall toward the axis. For more mild ion motion, this introduces a nonlinear perturbation to the focusing fields inside of the bubble. However, for extreme ion motion, the ion distribution collapses to a quasi-equilibrium characterized by a thin filament of extreme density on the axis which generates strong, nonlinear focusing fields. These fields can provoke unacceptable emittance growth that can be reduced through careful beam matching. In this paper, we discuss the rich physics of ion motion, give a brief overview of plans for the E-314 experiment at FACET-II which will experimentally demonstrate ion motion in plasma accelerators, and present results of particle-in-cell simulations of ion motion relevant to the E-314 experiment.