Simulation Design for Velocity-Controlled Spatio-Temporal Drivers in Laser Wakefield Acceleration

TL;DR

This paper presents a simulation workflow for modeling velocity-controlled spatio-temporal laser pulses in plasma wakefield acceleration, optimizing accuracy and computational efficiency.

Contribution

It introduces a Maxwell-consistent spectral construction for PIC simulations and discusses strategies to reduce simulation costs while maintaining fidelity.

Findings

Coupling of ST geometry affects wakefield excitation efficiency.

Scaling guidelines for near-resonant subluminal drivers are derived.

Continuous wall injection reduces transverse domain size without compromising propagation.

Abstract

Velocity-controlled spatio-temporal (ST) laser drivers offer a route to tailoring laser-plasma interactions by allowing the velocity of the intensity peak to be controlled independently of the envelope group velocity. In this work, we present a simulation-design workflow for PIC modelling of subluminal velocity-controlled ST pulses in OSIRIS based on a Maxwell-consistent spectral construction expressed as a superposition of exact vacuum solutions, and we describe its discrete k-space representation for numerical initialisation. We then examine wakefield excitation with velocity-controlled drivers, showing how the ST geometry couples the effective longitudinal extent of the high-intensity region to the transverse scale and deriving scaling guidelines for near-resonant excitation in the subluminal regime. Finally, we discuss the geometric constraints that make long-distance simulations costly, including focus-envelope slippage and strong transverse expansion, and we show that continuous wall injection can reproduce the intended vacuum propagation while substantially reducing the transverse domain size. Together, these results provide practical guidelines for accurate and computationally efficient PIC simulations of velocity-controlled ST drivers in wakefield-relevant regimes.