Numerical Studies on Divertor Plasmas in Helical Systems

"Scrape-off layer and divertor plasmas in helical systems are studied by using the two-dimensional (2D) numerical simulation code. Unified Edge Divertor Analysis code (UEDA code) is applied to the straight helical model of torsatron/helical heliotron configuraions. 2D profiles of plasma parameter, neutrals and imipurities are obtained. Erosion rate and neutral back flow rate to the core plasma are also evaluated. Various shapes of the buffle plate are examined from the view point of the establishment of ""dense-cold divertor plasma"" by which we can avoid the damage of the target plate.