Experimental realization of optimized NT scenarios with a detached edge

Demonstrate experimentally optimized negative triangularity scenarios that simultaneously maintain high-performance ELM-free operation and a detached plasma edge to establish reactor-relevant core–edge integration for negative triangularity configurations.

Background

The paper shows that strongly shaped NT plasmas on DIII-D are inherently ELM-free and can achieve competitive core performance, but the divertor configurations used lacked strong baffling or closed geometry and typically had short SOL connection lengths. While SOL conditions can strongly impact edge behavior and power handling, they are not responsible for NT’s ELM-free nature.

To advance NT towards reactor application, the authors emphasize the need to combine high-performance, ELM-free NT operation with a detached edge—critical for power exhaust and component protection—in an experimentally validated optimized scenario.

References

The physics understanding of the NT edge is still evolving rapidly, and many open questions remain. Additionally, the experimental realization of optimized NT scenarios, which feature high-performance ELM-free plasmas in conjunction with a detached edge, will go a long ways towards establishing the credibility of the NT regime as a reactor-relevant scenario.

— Characterization of the ELM-free Negative Triangularity Edge on DIII-D (2405.11082 - Nelson et al., 17 May 2024) in Section 6 (Conclusion)