HHFW coupling resistance assessment for different NSTX-U plasma scenarios using Petra-M FEM framework

NSTX-U will be equipped with the high harmonic fast wave (HHFW) antenna system with an injected power up to 6 MW. HHFW could play a major role in NSTX-U plasma particularly for driving current in the plasma ramping phase and providing a significant core electron heating. An evaluation of the antenna coupling resistance for different NSTX-U plasma scenarios, such as different scrape-off layer (SOL) density profiles and magnetic field values, is very desirable before the upcoming NSTX-U experimental campaign in order to assess the potential HHFW antenna performance. Here we employ the Petra-M FEM framework, which has been used to simulate the full NSTX-U torus including the SOL and the realistic antenna geometry. Full field plasma scenarios, which correspond to a toroidal magnetic field of B_T =1 T, will be examined in detail and compared with lower B_T field cases. A scan of SOL density values and antenna phasing will be also performed. Finally, an attempt will be made to relate the current numerical results shown in this work with previous HHFW coupling resistance measurements and predictions.