An extended kinetic model for the thermal force on impurity particles in weakly collisional plasmas

We have developed an extended kinetic model for the thermal force F∇∥T on test impurity particles in plasmas. This model makes use of a combination of the plasma ion heat flux qGM derived from the generalized moment equations (E. Zawaideh et al., Phys. Fluids 1988, 31) and the numerical algorithm presented earlier (Y. Homma, A. Hatayama, J. Comput. Phys. 2013, 250). The applicable condition extends from collisional to weakly collisional plasmas, and F∇∥T weakens when the plasma collisionality decreases. A test simulation is performed assuming a tentative weakly collisional plasma. The results show that it can have a non‐negligible influence on transient impurity transport in a DEMO‐scale tokamak to take into account the effect of plasma collisionality in thermal force modelling.