CIPS, Boulder, Colorado
This talk will review some of the recent advances of electromagnetic modeling with the inclusion of charged particles, as is important for beam physics and plasma physics. Important advances include methods for accurately treating boundaries for accelerator cavities, beam pipes, etc.; increasing the maximum stable time step; and algorithms that work well on parallel architectures. Higher-order algorithms with good properties are also of interest. Early cut-cell approaches failed to result in a symmetric linear system and, as a result, can be weakly damped or unstable. Later cut-cell approaches were shown to be symmetric, but they suffered from a reduction of the stable time step. Now available are cut-cell methods that can accurately model curvilinear boundaries with no reduction in stable time step. With Richardson extrapolation, these methods can give frequencies accurate to 1 part in 106 with less than 100 cells in each direction. The use of these new algorithms in VORPAL,* a flexible, object-oriented, massively parallel modeling application, will be presented. VORPAL has been used for a number of applications** involving the self-consistent interaction of charged particles with electromagnetic fields. Finally, we will discuss the needs for improvements to self-consistent EM modeling.
* C. Nieter and J. R. Cary, "VORPAL: a versatile plasma simulation code", J. Comp. Phys. 196, 448-472 (2004).
** C. G.R. Geddes, et al Nature 431, 538-541 (Sep. 2004)
SLAC, Menlo Park, California
Under the US DOE SciDAC project, SLAC has developed a suite of 3D (2D) Parallel Higher-order Finite Element (FE) codes, T3P (T2P) and PIC3P (PIC2P), aimed at accurate, large-scale simulation of wakefields and particle-field interactions in RF cavities of complex shape. The codes are built on the FE infrastructure that supports SLAC’s frequency domain codes, Omega3P and S3P, to utilize conformal tetrahedral (triangular) meshes, higher-order basis functions and quadratic geometry approximation. For time integration, they adopt an unconditionally stable implicit scheme. PIC3P (PIC2P) extends T3P (T2P) to treat charged particle dynamics self-consistently using the PIC approach, the first such implementation on the FE grid. Examples from applications to the ILC, LCLS and other accelerators will be presented to compare the accuracy and computational efficiency of these codes versus their counterparts using structured grids.
LBNL, Berkeley, California
LLNL, Livermore, California
We have developed a new, comprehensive set of simulation tools aimed at modeling the interaction of intense ion beams and electron clouds (e-clouds). The set contains the 3-D accelerator PIC code WARP and the 2-D "slice" e-cloud code POSINST, as well as a merger of the two, augmented by new modules for impact ionization and neutral gas generation. The new capability runs on workstations or parallel supercomputers and contains advanced features such as mesh refinement, disparate adaptive time stepping, and a new "drift-Lorentz" particle mover for tracking charged particles in magnetic fields using large time steps. It is being applied to the modeling of ion beams (1 MeV, 180 mA, K+) for heavy ion inertial fusion and warm dense matter studies, as they interact with electron clouds in the High-Current Experiment (HCX). We describe the capabilities and present recent simulation results with detailed comparisons against the HCX experiment, as well as their application (in a different regime) to the modeling of e-clouds in the Large Hadron Collider (LHC).
Fermilab, Batavia, Illinois