Modeling betatron radiation using particle-in-cell codes for plasma wakefield accelerator diagnostics

TL;DR

This paper develops a numerical model for betatron radiation in plasma wakefield accelerators, integrating particle trajectories from different simulation methods to support experimental diagnostics across a wide energy and angular range.

Contribution

It introduces a comprehensive numerical approach combining particle tracking and PIC simulations to model betatron radiation for accelerator diagnostics.

Findings

Validated model against analytical and PIC benchmarks

Simulated betatron spectra for FACET-II parameters

Demonstrated model's capability for wide energy and angular ranges

Abstract

The characterization of plasma wakefield acceleration experiments using emitted photons from betatron radiation requires numerical models in support of instrumentation of single-shot, double-differential angular-energy spectra. Precision characterization for relevant experiments necessitates covering a wide energy range extending from tens of keV through 10~GeV, with an angular resolution on the order of $100 \;\mu\text{rad}$. In this paper, we present a numerical model for betatron radiation from plasma accelerated beams, that are based on integration of Lienard Wiechert (LW) potentials for computed particle trajectories. The particle trajectories are generated in three different ways: first, by particle tracking through idealized fields in the blowout regime of PWFA; second, by obtaining trajectories from the Quasi-static Particle-in-Cell (PIC) code QuickPIC; and third, by obtaining trajectories from the full PIC code OSIRIS. We performed various benchmarks with analytical expressions and the PIC code EPOCH, which uses a Monte-Carlo QED radiation model. Finally, we present simulations of the expected betatron radiation for parameters from the Facility for Advanced Accelerator Experimental Tests II (FACET-II) PWFA and plasma photocathode experiments.