Efficient algorithm for high fidelity collisional charged particle beam dynamics

Abstract

High fidelity charged particle beam dynamics, especially if collisional, require specialized numerical methods. The challenges include the ability to deal with very large particle numbers, long-range electromagnetic forces, and vast spatial and timescales. We developed a novel algorithm to address these challenges. The main characteristics of the algorithm are Strang splitting to separate near and far forces, the fast multipole method to lower the computational cost of the far region, and the Simò integrator to capture all close encounters efficiently in the near region. The algorithm is fully adaptive both in space and time, while maintaining symplecticity to machine precision. Its performance is illustrated with two challenging examples from nonlinear multiparticle beam dynamics, including the first electron cooling simulations based on first principles.