Sheath Driven Impurity Modeling for Helicon Wave Operation in DIII-D

High-power helicon waves (~360 kW at 476 MHz) have been applied in DIII-D, demonstrating efficient radiofrequency (RF) heating. However, RF sheath rectification near antenna structures can enhance plasma-material interactions (PMI), leading to localized erosion and impurity generation. We use the STRIPE framework[1]—integrating SOLPS plasma backgrounds, COMSOL RF fields, RustBCA surface response, and GITR impurity transport—to assess PMI during L-mode discharge #195196. Results show erosion is highly sensitive to sheath potential and local plasma density, with low net erosion predicted under realistic edge conditions. Simulations reproduce key experimental signatures, including low impurity radiation, and inform operational strategies to mitigate PMI. STRIPE offers predictive capability for antenna design and impurity control in next-step devices.

[1] Kumar, A., et al., Integrated modeling of RF-Induced Tungsten erosion at ICRH Antenna structures in the WEST tokamak. Nuclear Fusion, vol. 65, no. 7, 2025, pp. 1-4.