Predictive Modeling of a Dissipative Divertor in DIII-D using SOLPS-ITER

A new dissipative divertor installation is planned in DIII-D to inform power exhaust physics issues in regimes pushed toward the conditions expected in a fusion pilot plant. SOLPS-ITER [1] simulations of a long leg divertor concept demonstrate impurity seeding requirements for achieving deep detachment and trade-offs due to reduced dissipation with divertor pumping for density control. Increasing the outer divertor leg length up to ~50 cm reveals benefits of enhanced dissipation due to longer connection lengths and increased stability of the radiation front between the X-point and target, avoiding a MARFE condition. Simulations are run with upstream separatrix electron density scanned around ~2x1019 m-3 and input powers up to 30 MW, which represents the potential of future electron cyclotron heating upgrades along with existing neutral beam injection.

[1] X. Bonnin et al., Plasma Fusion Res. 11, 1403102 (2016).