Hot VDE investigation of the negative triangularity plasmas based on HL-2M tokamak

Abstract Heating loads on the divertor has been the major issue for the tokamak operation. The innovative negative triangularity plasmas are considered to be of the favorable property for the power handling. Investigating the hot-plasma vertical displacement events of the negative triangularity plasma has an important significance for the future fusion reactors. In this paper, the hot-plasma vertical displacement event of the negative triangularity plasmas are investigated by the DINA code, based on the new medium-sized copper conducting tokamak HL-2M. Simulation results show that: (i) The initial vertical instability, of the negative triangularity configuration, develops much more faster than that of the positive triangularity configurations; (ii) During the hot VDE, larger absolute value of the negative triangularity causes speeder development of the initial vertical instability and severer mechanical loads; (iii) During the hot VDE of the negative triangularity plasma, the most non-uniform distribution of the electromagnetic force almost occurs in the outer part of the vacuum vessel. Therefore, an arc design of this part is recommended; (iv) The initial vertical instability, as well as the electromagnetic loads, can be mitigated, by further optimizing the magnetic structure around the divertor region.