Neoclassical impurity transport coefficients in HSX configurations*

Neoclassical impurity transport coefficients are calculated for quasi-helically symmetric and symmetry degraded configurations of HSX stellarator using SFINCS and PENTA codes. Trace amounts of carbon+6 and aluminum+12 impurities in a background hydrogen plasma are used in the calculations. Transport coefficients are found to be similar for both configurations for experimentally relevant plasma parameters. Calculations for aluminum impurity are compared with experimental transport coefficients obtained using a laser blow-off system. Initial experimental results indicate a much higher diffusivity and convection velocity than neoclassical values.