LBNL, Berkeley, California
LLNL, Livermore, California
It was shown recently that it may be computationally advantageous to perform computer simulations in a Lorentz boosted frame for a certain class of particle acceleration devices or problems such as: free electron laser, laser-plasma accelerator, and particle beams interacting with electron clouds*. However, even if the computer model relies on a covariant set of equations, it was pointed out that algorithmic difficulties related to discretization errors may have to be overcome in order to take full advantage of the potential speedup**. Further complications arise from the need to transform input and output data between the laboratory frame and the frame of calculation, but can be overcome at low additional computational cost***. We will present the theory behind the speed-up of numerical simulation in a boosted frame, our latest developments of numerical methods, and examples of application to the modeling of the above-cited problems and others if applicable.
LLNL, Livermore, California
PPPL, Princeton, New Jersey
LBNL, Berkeley, California
The near-term mission of the Heavy Ion Fusion Science Virtual National Laboratory (a collaboration of LBNL, LLNL, and PPPL) is to study "warm dense matter" at ~1 eV heated by ion beams; a longer-term topic is ion-driven target physics for inertial fusion energy. Beam bunch compression factors exceeding 50x have been achieved on the Neutralized Drift Compression Experiment (NDCX) at LBNL, enabling rapid target heating; however, to meet our goals an improved platform, NDCX-II, is required. Using refurbished induction cells from the decommissioned Advanced Test Accelerator at LLNL, NDCX-II will compress a ~500 ns pulse of Li+ ions to ~1 ns while accelerating it to 3-4 MeV (a spatial compression of 100-150x) over ~15 m. Non-relativistic ions exhibit complex dynamics; the beam manipulations in NDCX-II are actually enabled by strong longitudinal space charge forces. We are using analysis, an interactive 1D PIC code (ASP) with optimizing capabilities and a centroid-offset model, and both (r,z) and 3D Warp-code simulations, to develop the NDCX-II accelerator. Both Warp and LSP are used for plasma neutralization studies. This talk describes the methods used and the resulting physics design.