Modelling of ion kinetic effects for SOL flow formation

The plasma flow in the scrape-off layer (SOL) plays an important role for the control of heat and particle including impurity in magnetic fusion reactors. SOL flow patterns have recently been studied by the particle simulations, and the effects of finite-orbit-size of ions are found to be essential for the flow-pattern formation [Takizuka et al., Nucl. Fusion 49, 075038 (2009)]. Based on these simulation results, a new model of the edge plasma flow is developed by introducing the "ion-orbit-induced flow" to the fluid equations. A tokamak plasma is divided into three regions; core region, transition layer and SOL region. The "ion-orbit-induced flow" is modeled by separating untapped part and trapped part, and by taking account the collision effect and poloidal distribution. The "ion-orbit-induced flow" becomes large at the edge region.