IFS Seminar with Saeid Houshmandyar

Abstract: In this talk, the feasibility study of detecting non-Maxwellian electron distributions using an oblique view in ITER’s electron cyclotron emission (ECE) diagnostics will be presented. Discrepancies between electron temperatures measured by ECE and Thomson Scattering (TS) diagnostics, initially observed in JET and TFTR tokamaks, suggest the presence of non-Maxwellian features in the electron momentum distribution. These inconsistencies, which are expected to be more pronounced in ITER with core temperatures reaching ~25 keV, necessitate refined diagnostic capabilities. Previous studies have indicated that oblique viewing angles could enhance sensitivity to non-thermal electrons, prompting the inclusion of an oblique antenna in ITER’s ECE system. However, engineering constraints have limited the oblique viewing angle to 9.25°.This study utilizes GENRAY, a 3D ray-tracing code, to model ECE emissions under H-mode ITER scenarios with Maxwellian and non-Maxwellian electron distributions. Simulations consider X- and O-mode polarizations at both radial (0°) and oblique (9.25°) angles. Results indicate that while radial X-mode views are sensitive to non-Maxwellian distortions, oblique views enhance sensitivity to electron energies up to 35–45 keV. Higher cyclotron harmonics provide reliable temperature measurements, and a Fourier Transform Spectrometer (FTS) could be employed for improved spectral coverage. The findings confirm that the 9.25°oblique angle is sufficient for detecting non-Maxwellian distributions, which is critical for accurate temperature measurements in future reactor-grade tokamaks. Plans for study the ECE-TS discrepancies at JET-DT campaigns will be discussed.