Fixing E-field divergence in strongly nonlinear wakefields in homogeneous plasma

TL;DR

This paper introduces an improved analytical model for electron-plasma wakefields that accurately describes the electric field divergence in the bubble regime, especially relevant for low-amplitude wakefields like the Trojan horse regime.

Contribution

The paper presents a new phenomenological model that corrects the divergence issue in existing wakefield models for strongly nonlinear regimes.

Findings

Better description of electric field divergence in wakefields

Improved bubble shape modeling in low-amplitude regimes

Enhanced analytical tools for plasma acceleration regimes

Abstract

Available analytical wakefield models for the bubble and the blow-out regime of electron-plasma acceleration perfectly describe important features like shape, fields, trapping ratio, achievable energy, energy distribution and radial emittance. As we show, for wakefields with an extremely small amplitude these models fail to describe the accelerating electric field and its divergence in the wakefield rear. Since prominent parameter regimes like the Trojan horse regime of photocathode injection exhibit this feature, it is of great importance to work out analytical models that fix this problem; one possible model is introduced in this work. Using a phenomenological theory, we are able to better describe the divergence of the electric field and the bubble shape.