Mapping technique for stellarators

The Stochastic Mapping Technique (SMT), a highly efficient method to solve the five-dimensional drift kinetic equation in the long-mean-free-path regime, is presented in an application to stellarators. Within this method, the dimensionality of the problem is reduced to four dimensions through a discretization in one dimension. Instead of tracing test particles in the whole phase space, test particles are followed on particular Poincare cuts. With this approach, the computation time is reduced by a large factor compared to direct Monte Carlo methods. The SMT is applicable to stellarators with arbitrary magnetic field geometries and topologies. It can be used for any problem where currently conventional Monte Carlo methods are applied. In particular, it is well suited for modeling the distribution function of supra-thermal particles generated by auxiliary heating methods, for studies of stellarator transport properties and for a fast survey of a specific configuration in the whole phase space necessary for an estimation of α-particle confinement