The effect of inelastic collisions on the transport of alpha particles in ITER-like plasmas

Abstract

The effect of charge changes on the transport of alpha particles in ITER-like plasmas is studied with a numerical code that follows the exact particle trajectories and includes the effect of elastic and inelastic collisions. It is shown that charge changing processes can produce significant changes in the transport of alpha particles in the edge-SOL region. The addition of inelastic collisions actually reduces the alpha particle loss rate below the level obtained when only elastic (Coulomb) collisions are included. This is due to the inward flux produced by the neutral density gradient. Power losses, on the other hand, remain at approximately the same level because the average energy of the lost particles is higher when inelastic collisions are included. Finally, the spatial distribution of the lost particles changes significantly when inelastic collisions are added, with a larger fraction of the lost particles reaching the wall.