Accurate simulation of direct laser acceleration in a laser wakefield accelerator

Abstract

In a laser wakefield accelerator (LWFA), an intense laser pulse excites a plasma wave that traps and accelerates electrons to relativistic energies. When the pulse overlaps the accelerated electrons, it can enhance the energy gain through direct laser acceleration (DLA) by resonantly driving the betatron oscillations of the electrons in the plasma wave. The particle-in-cell (PIC) algorithm, although often the tool of choice to study DLA, contains inherent errors due to numerical dispersion and the time staggering of the electric and magnetic fields. Further, conventional PIC implementations cannot reliably disentangle the fields of the plasma wave and laser pulse, which obscures interpretation of the dominant acceleration mechanism. Here, a customized field solver that reduces errors from both numerical dispersion and time staggering is used in conjunction with a field decomposition into azimuthal modes to perform PIC simulations of DLA in an LWFA. Comparisons with traditional PIC methods, model equations, and experimental data show improved accuracy with the customized solver and convergence with an order-of-magnitude fewer cells. The azimuthal-mode decomposition reveals that the most energetic electrons receive comparable energy from DLA and LWFA.

10 pages, 5 figures, to submit to Physics of Plasmas

References in corpus (7)

• Generating multi-GeV electron bunches using single stage laser wakefield acceleration in a 3D nonlinear regime
• Synergistic Laser Wakefield/Direct Laser Acceleration in the Plasma Bubble Regime
• Implementation of a hybrid particle code with a PIC description in r-z and a gridless description in $\varphi$ into OSIRIS
• Novel Aspects of Direct Laser Acceleration of Relativistic Electrons
• Relativistic laser driven electron accelerator using micro-channel plasma targets
• Predominant Contribution of Direct Laser Acceleration to High-Energy Electron Spectra in a Low-Density Self-Modulated Laser Wakefield Accelerator
• Particle integrator for particle-in-cell simulations of ultra-high intensity laser-plasma interactions

Cited by in corpus (2)

• Direct laser acceleration in underdense plasmas with multi-PW lasers: a path to high-charge, GeV-class electron bunches
• Direct laser acceleration in varying plasma density profiles