Introduction of a multi-species collision operator in GT5D and its application to heavy impurity transport

Obrejan, K.; Idomura, Yasuhiro   ; Honda, Mitsuru*

To analyze heavy impurity transport, the gyrokinetic full-f Eulerian code GT5D was extended with an implicit collision solver based on a multi-species linear Fokker-Plank collision operator. In the collision solver, a Krylov subspace method is applied to a collision operator, which is given as a convection diffusion operator in velocity space, and severe CFL conditions of heavy impurities are resolved. In addition, flux coordinates are newly applied to resolve magnetic field structures with less grids, and collisional transport simulations are dramatically accelerated. A collisional transport benchmark of tungsten was conducted to verify the accuracy of GT5D.