Energy-resolved x-ray and neutron diagnostics in tokamaks: Prospect for plasma parameters determination

Abstract

In fusion plasmas, essential plasma parameters can be inferred from x-ray and neutron measurements. The analysis of emitted neutron spectra can give access to the fuel ion ratio and ion temperature, while the local x-ray plasma emissivity contains information about electron temperature, magnetic axis, and concentration of impurities that can be estimated with the help of dedicated tomographic inversion and synthetic diagnostic tools. We report on ongoing efforts dedicated to x-ray and neutron diagnostics of tokamak plasmas. A methodology to determine the core impurity concentration and electron temperature from multiple line-integrated x-ray measurements in different energy bands is introduced. It is first validated with synthetic measurements and then applied on WEST experimental data. Regarding neutron measurements, a thin-foil proton recoil spectrometer using a gas electron multiplier (GEM) detector is being developed to measure fast neutron energy spectra. The modeling of the energy response function of this NS-GEM prototype, intended for future applications of fusion plasma spectrometry, is presented and discussed.