CPU efficient numerical code for charged particle transport through insulating straight capillaries
A numerical code, labeled InCa4D, used for simulating CPU-efficiently the guiding of charged beam particles through insulating straight nano or macro capillaries, is presented in detail. The paper may be regarded as a walk through the numerical code, where we will detail how we sample the inserted beam with a given emittance, how we compute the charge deposition and charge dynamics at the interfaces of the insulating capillary, how we evaluate the electric field by accounting for imposed boundary conditions. The latter add surface polarization charges at the dielectric interfaces and free charges at conducting interfaces, which screen correctly the deposited charges. The electric field in InCA4D yields accurate relaxation rates and decay rates for both cases, namely where the outer surface of the straight capillary is covered by a grounded conducting paint or not. Eventually, we show how we evaluate CPU-efficiently the trajectories of the inserted charged particles, allowing to compute typically 10^6 trajectories in about two hours on a modern CPU.