Conceptual design of Thomson scattering system with high wavelength resolution in magnetically confined plasmas for electron phase-space measurements

Abstract: We discuss the conceptual design of a spatially-resolved spectroscopy system of Thomson scattering with high wavelength resolution capable of measuring the shape of electron velocity distribution functions in magnetically confined plasmas. We design a spatially-resolved spectrometer with 2560 wavelength channels. The estimated number of scattered photons in a single spectrometer channel is much larger than unity under the setup and plasma parameters at the Compact Helical Device (CHD), indicating that the shape of scattered spectra can be directly observed. We calculate the synthetic spectra with various plasma parameters and electron velocity distribution functions. The signal-to-noise ratio and accuracy of the estimated parameter are examined using the synthetic spectra assuming Maxwellian electron velocity distribution functions. We also discuss the feasibility of detecting non-Maxwellian electron velocity distribution functions with the high wavelength resolution spectrometer.