Gyrotropy-Induced Symmetry Breaking of Erosion Hot Spots on Antenna Limiters during High-Power Tokamak RF Operation: Mechanisms and Mitigation Strategies

Abstract

Ion Cyclotron Range of Frequencies (ICRF) heating is essential for creating plasma in next-generation fusion devices. ICRF antennas often produce hot spots, reducing reliability, material survivability, and overall plasma performance. We show that toroidal and poloidal asymmetries in these hot spots arise intrinsically from the wave physics' gyrotropy, and that they can be compensated for either by controlling the poloidal phasing or by modifying the limiter shapes, reducing total erosion by a factor $\sim$2 compared to state-of-the-art designs.