Snowflake Divertor Simulation for an HL-2M Conceptual Design

Abstract

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 × 1019/m3 with 10 MW heating power flowing into the SOL/divertor regions, the peak load at the outer divertor is 1.64 MW/m2 for the SF divertor, but it is 3.2 MW/m2 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.

A snowflake divertor: a possible solution to the power exhaust problem for tokamaks

“…This provides enough space to install the PF coils not only outside the blanket but also outside the TF coils. The PF coil location outside TF coils is assumed in design studies [10,11] of future tokamaks with SF divertors. The aforementioned misconception may be related to the fact that the SF configuration can also be created by the coils situated very near the separatrix, as is the case for the spherical torus NSTX [12].…”

Towards advanced divertor configurations on the J-TEXT tokamak

“…It is foreseen that more and more upcoming new experiments and devices will contribute to the development of advanced magnetic divertor configurations, such as HL-2M [27] and DTT [28]. These experiments should enable the development of an integrated divertor solution that can be based on one of the reviewed magnetic configurations, advanced target technologies, and compatibility with the core plasma requirements.…”

A review of radiative detachment studies in tokamak advanced magnetic divertor configurations

“…Indications of detachment were observed in the first EAST experiments [166]. Significant heat flux reduction was observed in SOLPS simulations of attached divertor regimes due to snowflake geometry effects in the planned HL-2M tokamak [167,168] and the Chinese Fusion Experimental Tokamak Reactor [169]. Modeling of detachment in snowflake divertor configurations for these devices is also starting [132,170].…”