Design, characterization, and modeling of the Charge eXchange Recombination Spectroscopy (CXRS) suite at the SMall Aspect Ratio Tokamak (SMART).

Abstract

Ion temperature, rotation, and density are key parameters to evaluate the performance of present and future fusion reactors. These parameters are critical for understanding ion heat, momentum, and particle transport, making it mandatory to properly diagnose them. A common technique to measure these properties is charge exchange recombination spectroscopy (CXRS). For characterizing positive and negative triangularity plasmas at the small aspect ratio tokamak, a poloidal array of gas puff based CXRS diagnostics will be measuring the ion properties in different poloidal positions. In this work, the modeling of the expected signal and spatial coverage using the FIDASIM code is presented. Furthermore, the design and characterization of the low field side midplane CXRS diagnostic are described. Each diagnostic is composed of a gas injection system, an optical system that collects the light emitted by the plasma, and a spectrometer. These systems will provide ion temperature, rotation, and density with a radial resolution of 3.75mm and a temporal resolution of 2.2ms.