Modelling of the soft X-ray tungsten spectra expected to be registered by GEM detection system for WEST

Abstract

Abstract. In the future International Thermonuclear Experimental Reactor (ITER), the interaction between the plasma and the tungsten chosen as the plasma-facing wall material imposes that the hot central plasma loses energy by X-ray emission from tungsten ions. On the other hand, the registered X-ray spectra provide alternative diagnostics of the plasma itself. Highly ionized tungsten emits extremely complex X-ray spectra that can be understood only after exhaustive theoretical studies. The detailed analyses will be useful for proper interpretation of soft X-ray plasma radiation expected to be registered on ITER-like machines, that is, Tungsten (W) Environment in Steady-state Tokamak (WEST). The simulations of the soft X-ray spectra structures for tungsten ions have been performed using the fl exible atomic code (FAC) package within the framework of collisional-radiative (CR) model approach for electron temperatures and densities relevant to WEST tokamak.

Conceptual design and development of GEM based detecting system for tomographic tungsten focused transport monitoring

“…Whereas high QDE should ensure good experimental conditions for measuring the W concentration in the whole plasma, the appropriate gas mixture is expected to be identified. Taking into account that the most intense emissions of W ions at ASDEX Upgrade (I-like W 21+ to Mn-like W 49+ ) are in the VUV to the SXR (∼1.5-3 keV) region covering the electron temperature range of 0.5-5.0 keV [25], as well as predictions for the WEST project [13], two gas compositions were selected. Initially, the Ar:CO 2 and Ar:CO 2 :CF 4 mixtures with 5 mm thick conversion layer are considered to be used for application in the detector chamber.…”

“…The array of two GEM detectors is expected to discriminate the energy of SXR photons together with their position reconstruction in vertical and horizontal locations enabling energy-resolved poloidal plasma tomography. Controlling tungsten impurities in the plasma center should be based on the analysis of the characteristic radiation of L/M lines emitted by tungsten (the highest intensity of radiation emitted from the plasma center) [13]. The main aim of the new X-ray diagnostics is to provide the monitoring of the radiation emitted by highly ionized metal impurities focusing on the emission of W lines in the region of 2-4 keV.…”