Closing the Gaps to Future Fusion Reactors on DIII-D

The DIII-D program is pursuing an ambitious plan to rapidly close critical design gaps to a Fusion Pilot Plant (FPP), support the FES mission to develop the scientific and technological foundation for a fusion energy source, and support the growth of a competitive U.S. fusion energy industry. Key scientific and technology gaps that can be addressed on DIII-D for an FPP include plasma interacting components, high performance core solutions, exhaust handling compatible with the core, and transient control. Over the next three years, major facility upgrades will allow DIII-D to access reactor-relevant physics regimes with increased emphasis on closing fusion materials and technology (FM&T) gaps. The electron cyclotron heating will be doubled to 10 gyrotrons totaling 7 MW injected to furnish low-torque electron heating and profile control. Additional upgrades under discussion are (1) a Dissipation Focused Divertor to investigate detachment front stability while radiating significant power through main ion neutrals, (2) a closed, pumped lower divertor for negative triangularity plasmas to explore detached conditions, and (3) a full metal wall to test the compatibility of reactor relevant materials with advanced core-edge scenarios. Together, these elements will enable reactor solutions to be pioneered and projected with confidence.