Development of Rapid Simulation Code for NBI Heating Analysis in LHD

We develop a rapid simulation code for neutral beam injection (NBI) heating analysis, FIT3D-RC, to evaluate the power deposition in NBI-heated plasmas of the Large Helical Device (LHD). This code evaluates the beam ion birth profile using the Gaussian process regression (GPR) model applied to precomputation results by the Monte Carlo simulation and calculates the power deposition profile by NBI heating based on the simple analytical solution of the Fokker-Planck equation. We apply this code to the NBI heating in LHD and compare the results with the conventional code (conv-FIT3D). We obtain good agreement in the power deposition profiles calculated by FIT3D-RC and that by conv-FIT3D. Furthermore, the calculation time is significantly reduced compared to the previously available codes. FIT3D-RC is expected to be used for the high-speed analysis and prediction of NBI-heated plasmas.