Accurate modeling of plasma acceleration with arbitrary order pseudo-spectral particle-in-cell methods

Jalas, Sören; Dornmair, Irene; Lehe, Rémi; Vincenti, Henri; Vay, Jean‐Luc; Kirchen, Manuel; Maier, Andreas R.

doi:10.1063/1.4978569

Cited by 35 publications

(21 citation statements)

References 28 publications

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“…For TWEAC, alternative solvers that change the numerical speed of light around the common direction of both electrons and lasers [73] cannot be directly applied due to the laser beams propagating in two different, nonaxial direction. Advanced PIC methods, such as spectral solvers [75,76], are expected to improve long-term numerical stability in future studies. For reducing the extended simulation time to solution required, a strategy could be to exploit the quasistationary acceleration conditions in reduced-physics simulations, such as quasistatic approximation [77] approaches.…”

Section: Numerical Challengesmentioning

confidence: 99%

Circumventing the Dephasing and Depletion Limits of Laser-Wakefield Acceleration

et al. 2019

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Compact electron accelerators are paramount to next-generation synchrotron light sources and freeelectron lasers, as well as for advanced accelerators at the TeV energy frontier. Recent progress in laserplasma driven accelerators (LPA) has extended their electron energies to the multi-GeV range and improved beam stability for insertion devices. However, the subluminal group velocity of plasma waves limits the final electron energy that can be achieved in a single LPA accelerator stage, also known as the dephasing limit. Here, we present the first laser-plasma driven electron accelerator concept providing constant acceleration without electrons outrunning the wakefield. The laser driver is provided by an overlap region of two obliquely incident, ultrashort laser pulses with tilted pulse fronts in the line foci of two cylindrical mirrors, aligned to coincide with the trajectory of the accelerated electrons. Such a geometry of laterally coupling the laser into a plasma allows for the overlap region to move with the vacuum speed of light, while the laser fields in the plasma are continuously being replenished by the successive parts of the laser pulses. Our scheme is robust against parasitic self-injection and self-phase modulation as well as drive-laser depletion and defocusing along the accelerated electron beam. It works for a broad range of plasma densities in gas targets. This method opens the way for scaling up electron energies beyond 10 GeV, possibly towards TeV-scale electron beams, without the need for multiple laser-accelerator stages.

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Section: Numerical Challengesmentioning

confidence: 99%

Circumventing the Dephasing and Depletion Limits of Laser-Wakefield Acceleration

et al. 2019

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“…Other than that, in theory the presented results should remain valid. Simulations are performed using A c c e p t e d M a n u s c r i p t the particle-in-cell (PIC) code FBPIC [32,33], in a two-dimensional axisymmetric geometry to allow for accurate modeling of the transverse dynamics. FBPIC uses a spectral, quasi-cylindrical algorithm which avoids spurious numerical dispersion, including the zero-order numerical Cherenkov effect [34].…”

Section: Tailored Plasma-density Profilesmentioning

confidence: 99%

Tailored plasma-density profiles for enhanced energy extraction in passive plasma beam dumps

Jakobsson¹,

Bonatto²,

Li³

et al. 2019

Plasma Phys. Control. Fusion

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“…As a consequence this solver enables infinite order, imposes no Courant time step limit in vacuum and has no numerical dispersion. By lowering the resolution needed to reach a required accuracy compared to FDTD solvers [6,7,9], PSATD-type solvers have the potential to strongly reduce the time-to-solution of a large class of problems.…”

Section: Contextmentioning

confidence: 99%

A generalized massively parallel ultra-high order FFT-based Maxwell solver

Kallala

Vay

Vincenti

2019

Computer Physics Communications

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Dispersion-free ultra-high order FFT-based Maxwell solvers have recently proven to be paramount to a large range of applications, including the high-fidelity modeling of high-intensity laser-matter interactions with Particle-In-Cell (PIC) codes. To enable a massively parallel scaling of these solvers, a novel parallelization technique was recently proposed, which consists in splitting the simulation domain into several processor sub-domains, with guard regions appended at each sub-domain boundaries. Maxwell's equations are advanced independently on each sub-domain using local shared-memory FFTs (instead of a single distributed global FFT). This implies small truncation errors at sub-domain boundaries, the amplitude of which depends on guard regions sizes and order of the Maxwell solver. For moderate guard region sizes, this 'local' technique proved to be highly scalable on up to a million cores and notably enabled the 3D modelling of so-called plasma mirrors, for which 8 guard cells only were enough to prevent truncation error growth. Yet, for other applications, the required number of guard cells might be much higher, which would severely limit the parallel efficiency of this technique due to the large volume of guard cells to be exchanged between sub-domains. In this context, we propose a novel parallelization technique that ensures very good scaling of FFT-based solvers with an arbitrarily high number of guard cells. Our 'hybrid' technique consists in performing distributed FFTs on local groups of processors with guard regions now appended to boundaries of each group of processors. It uses a dual domain decomposition method for the Maxwell solver and other parts of the PIC cycle to keep the simulation load-balanced. This 'hybrid' technique was implemented in the open source exascale library PICSAR. Benchmarks show that for a large number of guard cells (> 16), the 'hybrid' technique offers a ×3 speed-up and ×8 memory savings compared to the 'local' one.

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Accurate modeling of plasma acceleration with arbitrary order pseudo-spectral particle-in-cell methods

Cited by 35 publications

References 28 publications

Circumventing the Dephasing and Depletion Limits of Laser-Wakefield Acceleration

Circumventing the Dephasing and Depletion Limits of Laser-Wakefield Acceleration

Tailored plasma-density profiles for enhanced energy extraction in passive plasma beam dumps

A generalized massively parallel ultra-high order FFT-based Maxwell solver

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