Investigating Divertor-safe Burning-Plasma Regimes in ITER using a Core-edge Model with SOLPS Scalings

V. Graber, E. Schuster

Division of Plasma Physics (DPP) Annual Meeting of the American Physical Society (APS)

Spokane, WA, USA, October 17-21, 2022

To maximize fusion power, ITER will need to access burn regimes that push against operational limits. These limits include saturation of actuators such as neutral beam injectors and pellet injectors. Furthermore, the heat load on the divertor target should remain below 10 MW/m2 to avoid melting. Using Plasma Operation Contour (POPCON) plots based on a model coupling the plasma’s core with the scrape-off-layer and divertor regions, the temperature-density space of ITER plasmas is investigated in this work to determine which operational limits are most restrictive towards achieving higher fusion powers. In this core-edge model, the core-plasma region is governed by nonlinear density and energy response models, while the edge-plasma regions are modeled with scalings. These scalings were generated from SOLPS4.3 simulation results [1] and depend on the core-plasma's power and particle outflows, the separatrix impurity concentration, and the gas injection rate. Outputs of the scalings such as the neutral influx, the separatrix temperatures, and the separatrix densities enter into the core-plasma response models. In addition, the scalings yield the target's heat load which is crucial to identify the high-fusion-power regimes compatible with safe divertor operation.

[1] H.D. Pacher, et. al., J. Nucl. Mater. 463 (2015) 591–595.

*Supported by the US DOE under DE-SC0010661.