Scenario and shape development for consistent sample exposures in the wall materials thrust

2024 Research Campaign, Plasma Control

Purpose of Experiment

This Controls Development session will enable the success of FPP Candidate Wall Materials Thrust experiments. The thrust will be allocated 3 run days for material exposure experiments in FY24, all of which will use DiMES and LSN discharges. In order to maintain compatibility and comparability across the 3 run days, we need to develop a set of reference shots that the majority of proposals/session leaders can use. This will also optimize the use of run time for material exposure vs time lost to shot development. We will want to adjust the programmed strike point location, NBI power, and flux expansion at DiMES in order to optimize these shots during this Controls Development session. Precise strike-point control at DiMES will be a main focus of this experiment. We will implement a new ‘rastering’ control algorithm that sweeps the SP locally across DIMES. This experiment uses 195496 (H-mode) and 195969 (L-mode) as references for scenario development.

Experimental Approach

This controls development session will be conducted in two stages: 1) optimize the H-mode reference shot, and 2) optimize the L-mode reference shot. Since the H-mode reference is higher priority (higher heat/particle flux, larger radial variation, potential macroscopic material damage) and will require more time, that reference will be explored first. Under H-mode ELM-ing conditions, specialized DiMES configurations will allow samples to achieve FPP-relevant heat loads of 10-15 MW/m^2. The H-mode solution to be tested here is to locally sweep or raster the plasma strike point (SP) across the 5 cm DiMES surface, varying frequency, scan distance, and injected power to control local heat fluxes.

See more details, including project leads, at U.S. Department of Energy, Office of Scientific and Technical Information (OSTI).