Simulation of the motional stark effect on C-MOD using MSESIM and PERF

Abstract

The Motional Stark Effect (MSE) is used to measure the internal topology of the magnetic field and radial electric field in a tokamak plasma. MSESIM, a MSE simulation code originally developed for MAST, was transformed to simulate the MSE effect on C-MOD. This code was extended to simulate the Paschen Back Effect and the non statistical population of the energy levels. MSESIM was benchmarked against PERF, a different MSE simulation code developed for JET and C-MOD, to gain more confidence in the results of both codes. MSESIM has been used to investigate the influence of the collection optics, beam divergence, collection volume, Paschen Back Effect, non statistical population of the energy levels and the narrow bandpass filter on the spectrum and polarisation angle of C-MOD. The MSESIM simulation results were compared with measurement to assess how well the code simulates reality