Resonant RF Wakefield Coupling for Radiation-Reaction Control of 3D Betatron Dynamics in Hybrid Laser Plasma Accelerators

TL;DR

This paper explores how resonant RF fields can be used to control betatron dynamics and improve beam stability in hybrid laser plasma accelerators through theoretical, numerical, and simulation analyses.

Contribution

It introduces a method for using tunable RF fields to resonantly enhance beam stability and reduce emittance in hybrid laser plasma accelerators.

Findings

Resonant RF fields enable deterministic control of transverse beam dynamics.

Radiative damping reduces parasitic oscillations and emittance.

Stability maps reveal conditions for optimal beam quality.

Abstract

Hybrid laser plasma radiofrequency (RF) acceleration architectures signify a promising advancement in addressing the stability challenges associated with traditional laser wakefield accelerators. A thorough theoretical and numerical analysis of the three-dimensional dynamics of ultra-relativistic electron bunches in these hybrid systems is presented, clearly explaining how transverse beam stability, betatron oscillation polarisation, and radiative cooling work. By combining analytical models of spatiotemporal plasma wakefield modulation and phase dependent RF-driven oscillations with fully self-consistent 3D particle in cell (PIC) simulations, incorporating classical radiation reaction (RR) via the Landau Lifshitz model (with quantum parameter to account for synchrotron like losses during betatron oscillations. The findings indicate that the external RF fields operate as a tunable lattice, allowing for exact adjustment of amplitude, frequency, and carrier-envelope phase, which facilitates deterministic regulation of transverse focussing gradients and betatron amplitudes. A regime of resonant alignment between RF fields and natural betatron frequencies is established; this resonance enhances controlled transverse excursions while concurrently diminishing parasitic oscillations via increased radiative damping, resulting in substantial emittance reduction and the alleviation of synchrotron-like energy losses. Also, the detailed stability maps and 3D force landscapes show that the gamma factor growth rates change over time depending on the interaction between longitudinal field gradients and initial injection conditions. The paper's results give a clear picture of the nonlinear, resonant, and damping events that happen in hybrid accelerators. They also make it possible to get ultra stable, high-quality electron beams with the right polarisation states.