Rapid Low-Noise Simulation of Ultra-bright 10 GeV Electron Bunches in Laser Plasma Accelerators

The BELLA project at LBNL seeks to develop ~10 GeV laser-plasma accelerator stages that will produce ultra-short, low-divergence ~1 nC electron bunches, total energy spread of ~1% and slice energy spread of ~0.1%. A beam of sufficient brightness for collider applications can be used to drive a free electron laser and so this is an experimental goal for 2012. Simulation support is required to reduce technical risk and increase the chances of experimental success. However, traditional particle-in-cell (PIC) simulations suffer from high-frequency particle noise, which artificially increases the emittance and energy spread of the simulated electron bunch. Fundamentally new techniques are required to adequately suppress numerical noise. Our Phase II objective is to develop software that will reduce technical risk and help to improve the performance of next-generation laser-plasma accelerator (LPA) experiments. In Phase I, we will determine the best approach to accurate low-noise simulation of high charge, ultra-bright relativistic electron beams. Such extreme beams must be simulated as part of production LPA modeling, so we consider only finite-difference time domain electromagnetic techniques. We will consider an approach analogous to what is done in many particle tracking codes, in which self-fields (aka space charge forces) are calculated in the beam frame by solving Poisson