Deuterium Balmer/Stark spectroscopy and impurity profiles: first results from mirror-link divertor spectroscopy system on the JET ITER-like wall

TL;DR

This paper presents the first results from a redesigned mirror-link divertor spectroscopy system on JET, aiming to measure impurity fluxes and plasma parameters in the ITER-like wall for improved understanding of tungsten sputtering and detachment.

Contribution

The paper introduces a new spectroscopy system on JET that covers the tungsten strike plate with enhanced resolution, enabling detailed impurity and plasma flux measurements in the ITER-like wall.

Findings

Successful measurement of impurity fluxes (C, Be, O, W)

Comparison of plasma parameters with other diagnostics

Initial insights into tungsten sputtering and detachment behavior

Abstract

For the ITER-like wall, the JET mirror link divertor spectroscopy system was redesigned to fully cover the tungsten horizontal strike plate with faster time resolution and improved near-UV performance. Since the ITER-like wall project involves a change in JET from a carbon dominated machine to a beryllium and tungsten dominated machine with residual carbon, the aim of the system is to provide the recycling flux, equivalent, to the impinging deuterium ion flux, the impurity fluxes (C, Be, O) and tungsten sputtering fluxes and hence give information on the tungsten divertor source. In order to do this self-consistently, the system also needs to provide plasma characterization through the deuterium Balmer spectra measurements of electron density and temperature during high density. L-Mode results at the density limit from Stark broadening/line ratio analysis will be presented and compared to Langmuir probe profiles and 2D-tomography of low-n Balmer emission [1]. Comparison with other diagnostics will be vital for modelling attempts with the EDGE2D-EIRENE code[2] as the best possible data sets need to be provided to study detachment behaviour.