Particle simulation of detached plasma in the presence of diffusive particle loss and radiative energy loss

The effect of diffusive particle loss and radiative energy loss on the formation of detached plasma is studied by using a particle simulation code PARASOL. The density near the divertor plate is decreased by the diffusion, and temperature is decreased by the radiation. The temperature drop does not make the density high, because of the generation of supersonic flow near the plate. The condition of the supersonic flow is C≡(RΓ/Rp)Tplate/Tthroat<1 (RΓ: particle flux amplification factor; Rp: momentum flux reduction factor; Tplate: temperature at the plate; Tthroat: temperature at the throat), and the Mach number at the plate is given as M=C−1+C−2−1, which is larger than unity. The simulation results agree well with this expression. The relation between diffusion/radiation and the detached plasma is discussed; low density due to the supersonic flow can bring about the detachment easily.