Quasistatic capillary discharge plasma model

L C Steinhauer,W D Kimura

doi:10.1103/physrevstab.9.081301

Abstract

A one-dimensional, quasistatic model of a capillary discharge plasma has been developed. Such a plasma is useful as a medium to generate plasma waves for acceleration of electrons via processes such as laser wakefield acceleration or plasma wakefield acceleration. Another important characteristic of the plasma is its intrinsic parabolic density distribution near the center of the capillary, which can channel a laser beam along the capillary. The model is intended to be a design tool to aid in the selection of the capillary parameters in order to obtain desired plasma characteristics, e.g., plasma density and matched laser beam radius for guiding. An optional external axial magnetic field can be included, which improves the laser-channeling effect in some cases. The model also enables a measure of the potential for laser damage of the capillary wall. Results are presented for the design of a gas-filled capillary that will be tested during the staged electron laser acceleration--laser wakefield (STELLA-LW) experiment.

Highlights

Plasma-based, laser-driven acceleration of electrons requires a suitable plasma medium for creation of the plasma wave that accelerates the electrons
In plasma wakefield acceleration (PWFA) [1], an ultrashort electron beam (e-beam) pulse passes through the plasma generating plasma waves in its wake
In laser wakefield acceleration (LWFA) [2], an ultrashort laser pulse travels through the plasma and produces the wakefields

Summary

INTRODUCTION

Plasma-based, laser-driven acceleration of electrons requires a suitable plasma medium for creation of the plasma wave (i.e., wakefield) that accelerates the electrons. SM-LWFA [10] where a seed e-beam pulse creates wakefields via resonant PWFA and the laser pulse immediately follows to amplify the wakefields via SM-LWFA All these approaches require specific plasma densities. For LWFA, maintaining a certain minimum laser intensity impacts the capillary design because of the aforementioned laser-channeling effect produced by the density hollow in the center of the channel [11,12]. The motivation for the work discussed in this paper was to develop a capillary discharge model that incorporates all the plasma physics and is made to aid in the design of the capillary This model supports the staged electron laser acceleration –laser wakefield (STELLALW) experiment being performed at the Brookhaven.

Assumptions and model description

Model parameters

Model algorithm method

Comparison of quasistatic model with Bobrova simulation

Capillary discharge properties predicted by quasistatic model

LWFA Method