Calculation of heating and current drive inside magnetic islands through coupling MHD and ray-tracing simulations

In tokamaks, the excitation of neoclassical tearing modes (NTMs) can trigger rapid magnetic island growth, eventually leading to disruptions. One promising approach to suppress NTMs involves heating and current drive within the magnetic islands. The efficiency of current drive can be significantly enhanced through localized heating and the RF condensation effect (A.H. Reiman and N.J. Fisch, Phys. Rev. Lett. 121(22), 225001 (2018)), previously simulated using the OCCAMI code (R. Nies, et al., Physics of Plasmas 27(9), 092503 (2020)). To conduct a self-consistent simulation of magnetic island evolution in the presence of RF heating, we have developed an interface to link the MHD simulation code M3D-C1 and the ray-tracing code GENRAY, aimed at validating the effectiveness of this disruption avoidance method. The M3D-C1 simulation outputs, which include plasma density, temperature, and magnetic fields, are accessible via the Fusion-IO library. GENRAY directly reads these outputs for ray-tracing calculations. We have enhanced the interface between Fusion-IO and M3D-C1 using the ADIOS2 library to improve parallel I/O efficiency. The results of ray-tracing calculations, such as power deposition and current drive efficiency, are then fed back into M3D-C1 as source terms. This integrated model allows us to replicate the current condensation effect previously studied by OCCAMI. Furthermore, we demonstrate the suppression of magnetic island growth in the presence of RF heating and current drive.