Toroidal soft x-ray array on the EXL-50 spherical tokamak

Abstract

A toroidal soft x-ray array system for spectrum and intensity measurements on the EXL-50 spherical tokamak is described. Silicon drift detectors and digital multichannel analyzers are adopted for all 21 channels of the array, and an average energy resolution of 147 eV at 5.89 keV has been achieved at count rates over 500 kcps. In total, 20 channels of the array are symmetrically observed in both co- and counter-current directions on the EXL-50 mid-plane with a spatial resolution of around 10 cm, and the remaining one serves as a background reference channel. Tungsten emissions from tungsten coating of the limiters on the central post are observed. The influence of hard x rays on measured soft x-ray spectra and system operation is discussed.

Electron Temperature Measurements Using a Two-Filter Soft X-ray Array in VEST

“…The PHA measures the energy spectrum of soft X-rays that pass through a single X-ray filter to estimate T e . In previous studies, silicon drift detectors (SDD) are commonly used for applying PHA to several fusion devices [8][9][10]. However, due to energy resolution (~180 eV) [11] and low detection efficiency of SDD below 1 keV [12], applying PHA to sub-keV range is challenging.…”