Snowflake Divertor Simulation for an HL-2M Conceptual Design

A conceptual design study of the HL-2M facility has shown that one can create not only a standard single-null divertor configuration on it,but also a second-order null(snowflake(SF))configuration.For the SF divertor,the magnetic flux expansion closes to the separatrix and exceeds that of the standard configuration by more than a factor of 4 at the outer divertor.The heat load at the divertor targets of this innovative configuration has been investigated by using B2.5-Eirene.It is shown that the heat load it targets is different from that of the standard configuration.As a result of the magnetic flux expansion,the peak heat load reduces and does not concentrate on a small area near the separatrix.The heat load profile becomes flat as compared to the standard divertor.When the upstream density is 2.0×10^(19)/m^(3) with 10 MW heating power flowing into the SOL/divertor regions,the peak load at the outer divertor is 1.64 MW/m^(2) for the SF divertor,but it is 3.2 MW/m^(2) for the standard divertor,so the SF divertor can mitigate the heat load at the divertor targets when HL-2M operates at low plasma density and high heating power.