ICAP2012 - List of Authors (Vay, J.-L.)

Paper

Title

Page

Low Noise Particle-in-Cell Simulations of Laser Plasma Accelerator 10 GeV Stages

78

E. Cormier-Michel, D.L. Bruhwiler, J.R. Cary, B.M. Cowan, E.J. Hallman
Tech-X, Boulder, Colorado, USA
E. Esarey, C.G.R. Geddes, W. Leemans, C.B. Schroeder, J.-L. Vay
LBNL, Berkeley, California, USA

Funding: Work supported by DOE/HEP, under grants DE-SC0004441 and DE-FC02-07ER41499, including use of NERSC under DE-AC02-05CH11231.
Because of their ultra-high accelerating gradient, laser plasma based accelerators (LPA) are contemplated for the next generation of high-energy colliders and light sources. The upcoming BELLA project will explore acceleration of electron bunches to 10 GeV in a 1 meter long plasma, where a wakefield is driven by a PW-class laser. Particle-in-cell (PIC) simulations are used to design the upcoming experiments where boosted frame simulations are used to model the full scale stages. As criteria on energy spread and beam emittance become more stringent, PIC simulations become more challenging as high frequency noise artificially increases those quantities. We show that calculating the beam self-fields using a static Poisson solve in the beam frame dramatically reduces particle noise, allowing for more accurate simulation of the beam evolution. In particular, this method gets correct cancellation of the transverse self-electric and magnetic fields of the beam, eliminating artificial self-forces, which is usually not true when using the standard PIC algorithm based on the staggered (“Yee”) electromagnetic field solver.

Slides TUSBC2 [5.989 MB]

THP07

Some Computational Challenges in the Modeling of Accelerators and their Solutions in the Simulation Code Warp

233

J.-L. Vay, C. Benedetti
LBNL, Berkeley, California, USA
R.H. Cohen, A. Friedman, D.P. Grote
LLNL, Livermore, California, USA

Funding: Supported by US-DOE Contracts DE-AC02-05CH11231 and DE-AC52-07NA27344, and the SciDAC/ComPASS project. Used resources of NERSC, supported by US-DOE Contract DE-AC02-05CH11231.
The Particle-In-Cell Code-Framework Warp originated in the Heavy Ion Fusion program to guide the development of accelerators that can deliver beams suitable for implosion of inertial fusion capsules. The range of application of Warp has considerably widened far beyond the initial area and it is now applied to the study and design of existing and next-generation high-energy accelerators, including, for example, the study of laser wakefield acceleration and electron cloud effects. We present an overview of Warp's capabilities, summarizing recent original numerical methods that were developed to address computational challenges such as space and time scale disparities, spurious numerical dispersion, efficient wideband digital filtering on parallel platforms, etc. The original methods include simulations in Lorentz boosted frames, an electromagnetic solver with tunable numerical dispersion and efficient stride-based digital filtering, Particle-In-Cell with Adaptive Mesh Refinement, a large-timestep ‘‘drift-Lorentz'' mover for arbitrarily magnetized species, and a relativistic Lorentz invariant leapfrog particle pusher. Selected examples of applications will be given.

Paper	Title	Page
TUSBC2	Low Noise Particle-in-Cell Simulations of Laser Plasma Accelerator 10 GeV Stages	78
	E. Cormier-Michel, D.L. Bruhwiler, J.R. Cary, B.M. Cowan, E.J. Hallman Tech-X, Boulder, Colorado, USA E. Esarey, C.G.R. Geddes, W. Leemans, C.B. Schroeder, J.-L. Vay LBNL, Berkeley, California, USA
	Funding: Work supported by DOE/HEP, under grants DE-SC0004441 and DE-FC02-07ER41499, including use of NERSC under DE-AC02-05CH11231. Because of their ultra-high accelerating gradient, laser plasma based accelerators (LPA) are contemplated for the next generation of high-energy colliders and light sources. The upcoming BELLA project will explore acceleration of electron bunches to 10 GeV in a 1 meter long plasma, where a wakefield is driven by a PW-class laser. Particle-in-cell (PIC) simulations are used to design the upcoming experiments where boosted frame simulations are used to model the full scale stages. As criteria on energy spread and beam emittance become more stringent, PIC simulations become more challenging as high frequency noise artificially increases those quantities. We show that calculating the beam self-fields using a static Poisson solve in the beam frame dramatically reduces particle noise, allowing for more accurate simulation of the beam evolution. In particular, this method gets correct cancellation of the transverse self-electric and magnetic fields of the beam, eliminating artificial self-forces, which is usually not true when using the standard PIC algorithm based on the staggered (“Yee”) electromagnetic field solver.
	Slides TUSBC2 [5.989 MB]

THP07	Some Computational Challenges in the Modeling of Accelerators and their Solutions in the Simulation Code Warp	233
	J.-L. Vay, C. Benedetti LBNL, Berkeley, California, USA R.H. Cohen, A. Friedman, D.P. Grote LLNL, Livermore, California, USA
	Funding: Supported by US-DOE Contracts DE-AC02-05CH11231 and DE-AC52-07NA27344, and the SciDAC/ComPASS project. Used resources of NERSC, supported by US-DOE Contract DE-AC02-05CH11231. The Particle-In-Cell Code-Framework Warp originated in the Heavy Ion Fusion program to guide the development of accelerators that can deliver beams suitable for implosion of inertial fusion capsules. The range of application of Warp has considerably widened far beyond the initial area and it is now applied to the study and design of existing and next-generation high-energy accelerators, including, for example, the study of laser wakefield acceleration and electron cloud effects. We present an overview of Warp's capabilities, summarizing recent original numerical methods that were developed to address computational challenges such as space and time scale disparities, spurious numerical dispersion, efficient wideband digital filtering on parallel platforms, etc. The original methods include simulations in Lorentz boosted frames, an electromagnetic solver with tunable numerical dispersion and efficient stride-based digital filtering, Particle-In-Cell with Adaptive Mesh Refinement, a large-timestep ‘‘drift-Lorentz'' mover for arbitrarily magnetized species, and a relativistic Lorentz invariant leapfrog particle pusher. Selected examples of applications will be given.