New Developments in the Simulation of Advanced Accelerator Concepts

Abstract

Abstract. Improved computational methods are essential to the diverse and rapidly developing field of advanced accelerator concepts. We present an overview of some computational algorithms for laser-plasma concepts and high-brightness photocathode electron sources. In particular, we discuss algorithms for reduced laser-plasma models that can be orders of magnitude faster than their higher-fidelity counterparts, as well as important on-going efforts to include relevant additional physics that has been previously neglected. As an example of the former, we present 2D laser wakefield accelerator simulations in an optimal Lorentz frame, demonstrating >10 GeV energy gain of externally injected electrons over a 2 m interaction length, showing good agreement with predictions from scaled simulations and theory, with a speedup factor of ~2,000 as compared to standard particle-in-cell.

Scaled simulations of a 10 GeV accelerator

“…The linear theory predicts that, for the parameters given above, an energy gain of 100 MeV is obtained at n 0 = 7 × 10 18 cm −3 and 10 GeV is achieved at n 0 = 7 × 10 16 cm −3 . A gain of 8 GeV has been demonstrated with test particles using a simulation in the boosted frame in 1D at 10 17 cm −3 [12,13], consistent with the linear theory which predicts a gain of 7 GeV in this case. By using test particles in the PIC simulations, we find that because the wake is slightly non-linear, 97 MeV and 1120 MeV can be achieved respectively at 10 19 and 10 18 cm −3 .…”

Numerical methods for instability mitigation in the modeling of laser wakefield accelerators in a Lorentz-boosted frame

“…However, as noted in [9], full scale simulations using the laboratory frame of 10 GeV stages at plasma densities of 10 17 cm À3 are not practical on present computers in 2D and 3D. At this density, the wake relativistic factor c w % 132, and 2-1/2D and 3D simulations were done in boosted frames up to c ¼ 130 to evaluate which numerical techniques are required to allow such simulations.…”

Modeling of 10 GeV-1 TeV laser-plasma accelerators using Lorentz boosted simulations

“…10 Simulations of parameters relevant to such a 10 GeV stage demand as many as 5000 processor hours for a one-dimensional simulation on a National Energy Research Scientific Computing Center (NERSC) supercomputer. 11 Various reduced models have been developed to allow multidimensional simulations at manageable computational costs: fluid approximation, [12][13][14] quasistatic approximation, 12,[15][16][17][18] laser envelope models, 12,14,16,17,19 and scaled parameters. 20,21 However, the various approximations that they require result in a narrower range of applicability.…”