Adaptive SIMD optimizations in particle-in-cell codes with fine-grain particle sorting

After the introduction of the ionization-injection scheme in Laser Wake Field Acceleration and of related high-quality electron beam generation methods as two-color or the Resonant Multi Pulse Ionization injection (ReMPI), the theory of thermal emittance by C. Schroeder et al. , has been used to predict the beam normalised emittance obtainable with those schemes. We recast and extend such a theory, including both higher order terms in the polinomial laser field expansion and non polinomial corrections due to the onset of saturation effects on a single cycle. Also, a very accurate model for predicting the cycle-averaged distribution of the extracted electrons, including saturation and multi-process events, is proposed and tested. We show that our theory is very accurate for the selected processes of Kr 8 + →10 + and Ar 8 + →10 + , resulting in a a maximum error below 1% even in deep saturation regime. The accurate prediction of the beam phase-space can be implemented e.g. in laser-envelope or hybrid PIC/fluid codes, to correctly mimic the cycle-averaged momentum distribution without the need of resolving the intra-cycle dynamics. We introduce further spatial averaging, obtaining expressions for the whole-beam emittance fitting with simulations in a saturated regime, too. Finally, a PIC simulation for a LWFA injector in the ReMPI configuration is discussed.

show abstract

“…We report here the set-up of the PIC simulations with the code Smilei [29,47] used to obtain Figs. 4,5,6,7,9.…”

Section: Set-up For the Pic Simulations Of Single-cycle Ionizationmentioning

confidence: 99%

Accurate electron beam phase-space theory for ionization-injection schemes driven by laser pulses

Tomassini

Massimo

Labate

et al. 2021

High Pow Laser Sci Eng

View full text Add to dashboard Cite

show abstract

“…They use a total of 200 MPI processes and 16 OpenMP threads per process. Smilei scalar operators are used [9] so performances scale linearly with the number of MP. Hyperthreading is not activated.…”

Section: Numerical Setupmentioning

confidence: 99%

“…On the other hand, high performance computing (HPC) optimizations intend to improve the algorithm efficiency and scalability in order to reach higher resolutions and therefore better accuracy. This includes sorting techniques [5][6][7], vectorization [8,9], load balancing [7,10], advanced programming models [11], etc. These improvements are done at the cost of an increased complexity which sometimes prevent their combination.…”

Section: Introductionmentioning

confidence: 99%

Single Domain Multiple Decompositions for Particle-in-Cell simulations

Derouillat,

Beck

2019

Preprint

View full text Add to dashboard Cite

As a multi-purpose Particle-In-Cell (PIC) code, Smilei gathers many different features in a single software. Combining some of them is challenging. In particular, spectral solvers and patch based load balancing have a priori non compatible requirements. This paper introduces the Single Domain Multiple Decompositions (SDMD) method in order to address this issue. To do so, different domain decompositions are used for fields and particles operations. This approach allows to keep small domains for particles, necessary for a good load balancing, while having large domains for the fields. It proves beneficial in mitigating synchronization costs and gives the opportunity to introduce more paralellism in the PIC algorithm on top of providing structures compatible with spectral solvers.

show abstract

“…the initialization of the longitudinal momentum of the electrons created by ionization, and an extension of the tunneling ionization modeling procedure described in [34] is proposed, to obtain accurate results also for a 0 > 1. This extended procedure has been implemented in the open source PIC code Smilei [42,43], used for the simulations of the manuscript. In an unified framework, Smilei can run both standard laser and envelope simulations, in Cartesian geometries [36] and quasi-cylindrical geometry [38], the latter used for the simulations of this manuscript.…”

Section: Introductionmentioning

confidence: 99%

Numerical modeling of laser tunneling ionization in Particle in Cell Codes with a laser envelope model

Massimo,

Beck,

Dérouillat

et al. 2020

Preprint

View full text Add to dashboard Cite

The resources needed for Particle in Cell simulations of Laser Wakefield Acceleration can be greatly reduced in many cases of interest using an envelope model. However, the inclusion of tunneling ionization in this time averaged treatment of laser-plasma acceleration is not straightforward, since the statistical features of the electron beams obtained through ionization should ideally be reproduced without resolving the high frequency laser oscillations. In this context, an extension of an already known envelope ionization procedure is proposed, valid also for laser pulses with higher intensities, which consists in adding the initial longitudinal drift to the newly created electrons within the laser pulse ionizing the medium. The accuracy of the proposed procedure is shown with both linear and circular polarization in a simple benchmark where a nitrogen block is ionized by a laser pulse, and in a more complex benchmark of laser plasma acceleration with ionization injection in the nonlinear regime. With this addition to the envelope ionization algorithm, the main phase space properties of the bunches injected in a plasma wakefield with ionization by a laser (charge, average energy, energy spread, rms sizes, normalized emittance) can be estimated with accuracy comparable to a nonenvelope simulation with significantly reduced resources, even in cylindrical geometry. Through this extended algorithm, preliminary studies of ionization injection in Laser Wakefield Acceleration can be easily carried out even on a laptop.

show abstract

Adaptive SIMD optimizations in particle-in-cell codes with fine-grain particle sorting

Cited by 16 publications

References 38 publications

Accurate electron beam phase-space theory for ionization-injection schemes driven by laser pulses

Accurate electron beam phase-space theory for ionization-injection schemes driven by laser pulses

Single Domain Multiple Decompositions for Particle-in-Cell simulations

Numerical modeling of laser tunneling ionization in Particle in Cell Codes with a laser envelope model

Contact Info

Product

Resources

About