Study of the specific detachment characteristics of HL-2A

Numerical analysis of HL-2A single null and double null divertor discharges was done using the two-dimensional edge plasma simulation code SOLPS5.0. The detachment characteristic of HL-2A is determined by the specific divertor geometry of HL-2A. Its thin divertor throats are transparent for neutrals, but still quite well baffled towards the main chamber due to the long baffle lengths. This results in momentum losses at low densities from the interaction of the streaming divertor plasma with this neutral cushion. Therefore, a strong deviation from the common 2-point scaling is observed if local parameters are used, similar to island divertor in stellarator. The thin divertor throats in HL-2A pose MHD shaping problems resulting in strongly enhanced main chamber losses, because a large amount of the power is lost at baffles and does not even get into the divertor.