GEM-PIC-RZ: a Galilean electromagnetic particle-in-cell code in quasi-cylindrical geometry with nonuniform grids
Abstract
Laser-plasma accelerators span scales from the micrometre wavelength of the driving laser to acceleration lengths of millimetres or metres. Full particle-in-cell (PIC) simulations resolve the laser carrier but are constrained by the Courant condition, whereas quasi-static models are computationally efficient but do not resolve it. We present GEM-PIC-RZ, a quasi-cylindrical implementation of the Galilean electromagnetic PIC scheme. The method retains the slow evolution of the forward field and therefore resolves the laser carrier while allowing a propagation step governed by the evolution of the laser and plasma rather than by the cell size. User-defined nonuniform grids and a charge-conserving regularization of the bubble closure support efficient simulations across these scales. Comparisons with the full PIC code FBPIC show agreement for the laser wake, the depletion and redshift of a few-cycle pulse, and ionization injection; the measured CPU time is about 2\,\% of that for FBPIC in the reported runs; the injected charge carries a model uncertainty of about 15\,\% from the regularization. An envelope model, in contrast, underestimates the depletion of the few-cycle pulse fivefold. Self-injection in a sharp density down-ramp is not yet reproduced and remains an open problem.
Related
- First-principles simulation of free-electron lasers with the Galilean electromagnetic particle-in-cell method: even harmonics of planar undulators
- X-dispersionless solver for electromagnetic and axion fields in a cylindrical particle-in-cell code
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- Measurement-induced spatially nonuniform fluctuations of the local particle number and their crossover in a quasiperiodic free-fermion chain
BibTeX
@misc{pukhov2026gempicrz,
title = {{GEM-PIC-RZ: a Galilean electromagnetic particle-in-cell code in quasi-cylindrical geometry with nonuniform grids}},
author = {Alexander Pukhov},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.31622},
eprint = {2610.31622},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.31622},
}
RIS
TY - UNPB
TI - GEM-PIC-RZ: a Galilean electromagnetic particle-in-cell code in quasi-cylindrical geometry with nonuniform grids
AU - Alexander Pukhov
PY - 2026
DA - 2026/10/22
PB - arXiv
DO - 10.48550/arxiv.2610.31622
UR - https://arxiv.org/abs/2610.31622
AB - Laser-plasma accelerators span scales from the micrometre wavelength of the driving laser to acceleration lengths of millimetres or metres. Full particle-in-cell (PIC) simulations resolve the laser carrier but are constrained by the Courant condition, whereas quasi-static models are computationally efficient but do not resolve it. We present GEM-PIC-RZ, a quasi-cylindrical implementation of the Galilean electromagnetic PIC scheme. The method retains the slow evolution of the forward field and therefore resolves the laser carrier while allowing a propagation step governed by the evolution of the laser and plasma rather than by the cell size. User-defined nonuniform grids and a charge-conserving regularization of the bubble closure support efficient simulations across these scales. Comparisons with the full PIC code FBPIC show agreement for the laser wake, the depletion and redshift of a few-cycle pulse, and ionization injection; the measured CPU time is about 2\,\% of that for FBPIC in the reported runs; the injected charge carries a model uncertainty of about 15\,\% from the regularization. An envelope model, in contrast, underestimates the depletion of the few-cycle pulse fivefold. Self-injection in a sharp density down-ramp is not yet reproduced and remains an open problem.
ER -