A Performance Upgrade to Resolve the Physics of the ITEP Gap with DIII-D

The critical challenge for a viable concept for a fusion pilot plant is to resolve a highly dissipative divertor and its compatibility with a high-performance core. An upgrade to DIII-D is proposed to close gaps on reactor physics regimes in divertor, SOL, pedestal and core, to test critical physics, pioneer solutions and resolve their mutual compatibility. The key is to raise pressure. This enables high density to be sustained at low collisionality to marry a high dissipation divertor with a high-performance core. This is achieved through a rise in shaping, field, current and RF power, exploiting the natural properties of improved pedestals at high shape to close gaps and push limits. The increased parallel heat flux and density raise opacity and shorten mean free paths to access reactor relevant physics in the divertor. This also shortens neutral penetration depths into the core to study relevant particle and impurity transport with unique access into low collisionality, thermalized, peeling limited reactor-like regimes. A modular divertor, high Z wall coatings and DIII-D’s flexible plasma configurations then provide the range to test physics, solutions and their materials compatibility in divertor and core in order to resolve and project the approach for the pilot.