Implementation and validation of guiding centre approximation into ERO2.0

The Monte-Carlo code ERO2.0 uses full orbit resolution to follow impurity particles throughout the plasma volume to determine the local erosion and deposition fluxes on the plasma-facing components of fusion devices in magnetic confinement fusion. To have direct comparisons to other transport codes (e.g., ASCOT and DIVIMP) and to accelerate the code, guiding centre approximation (GCA) was implemented into ERO2.0. In addition, a hybrid simulation mode for ERO2.0 was developed, in which the advantages of both full orbit resolution and guiding centre approximation are used. In typical scenarios in this simulation mode, full orbit resolution is applied exclusively near the wall region, while GCA is used everywhere else along a particle's trajectory. Special emphasis was put on the validation of the implementation by an inner-code benchmarking to pure full orbit simulations. Analysed scenarios included test plasmas with simplified geometry and a realistic test case corresponding to a deuterium limiter plasma used in JET pulse #80319. The results of simulations performed in the hybrid simulation mode are in very good agreement to corresponding pure full orbit simulations, while a significant code speed-up was achieved.