KSTAR grant PI Frerichs

Title:“Physics Basis, Optimization, and Control for Integrated 3D Edge Long-pulse Tokamak Scenarios”

J.-K. Park, Princeton Plasma Physics Laboratory (Lead Principal Investigator)
C. Paz-Soldan, General Atomics (Co-Lead Principal Investigator)
H. Frerichs, University of Wisconsin-Madison (Institutional Principal Investigator)
Z. Lin, University of California-Irvine (Institutional Principal Investigator)
E. Kolemen, Princeton University (Institutional Principal Investigator)

Public Abstract:

This project aims to leverage the unique research capabilities of international tokamak facilities to develop a unified physics basis, predictive capability, and long-pulse demonstration for the control of edge-localized modes (ELMs) with optimized non-axisymmetric (3D) fields. ELMs constitute a major challenge to the operation of fusion-grade tokamak plasmas such as ITER due to the large impulsive heat loads delivered to plasma-facing components during ELM excitation. US scientists pioneered the development of the 3D field approach to ELM control and have since played a crucial role in exporting the technique to international facilities such as the KSTAR tokamak in Korea, the EAST tokamak in China, and the AUG tokamak in Germany. As a result of this work, 3D fields are now foreseen as the primary ELM control technique for ITER. This project complements active work on US domestic facilities to further understand and optimize the 3D field ELM control technique by enabling access to the unique plasma regimes and long-pulse operation available on the aforementioned international facilities, and thus expands the viability and applicability of this US-pioneered control technique towards the ITER era.

The project addresses high-priority research questions and necessary operational demonstrations sequentially, with the ultimate goal of a developing predictive capability for optimized 3D coil and plasma scenario design, culminating in demonstrating long-pulse stationary ELM suppressed discharges in KSTAR. The proposal is structured into six cross-cutting tasks: Task 1 focuses on targeted experiments to resolve open issues in ELM suppression access criteria leveraging the key capabilities of international facilities. Task 2 uses this information to develop empirical and first-principles scaling laws for extrapolation. Task 3 enhances the predictive understanding of the transport changes implicit in the earlier tasks and validates key scaling trends. Task 4 applies earlier results to the prediction and optimization of divertor heat flux profiles in ELM suppressed scenarios. Task 5 develops real-time control of key actuators to enable routine long-pulse ELM suppressed operation. Finally, the scaling laws are further applied in Task 6 to the development of innovative 3D coils to isolate the spectral components of interest for more reactor relevant 3D field ELM control.

Funding Information: funded by the Department of Energy, Office of Fusion Energy Science, DE-SC0020357