TriWaSp: a multi-faceted visible spectroscopy diagnostic on the ST40 tokamak

• Published in: Journal of instrumentation Vol. 18; no. 3; p. C03023
• Main Authors: Willett, H.V., Osin, D., Naylor, G., Wood, J., Lomanowski, B., Sertoli, M.
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.03.2023; Institute of Physics (IOP)
• Subjects: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Charge exchange; charged-particle spectroscopy; Configuration management; interferometry; Ion charge; Ion temperature; Low aspect ratio; Neon; Plasma diagnostics — charged-particle spectroscopy; Plasma diagnostics — interferometry, spectroscopy and imaging; Spectrometers; Spectroscopy; Tokamak devices; Velocity distribution
• ISSN: 1748-0221; 1748-0221
• DOI: 10.1088/1748-0221/18/03/C03023

Abstract We present a new state-of-the-art Triple Wavelength Spectrometer (TriWaSp), recently deployed on ST40, a high field low aspect ratio spherical tokamak. The TriWaSp has a range of possible applications due to its flexible design; the current configuration focuses on charge exchange recombination spectroscopy from carbon and neon impurities in the ST40 plasma. This paper discusses the detailed setup of the system and presents initial charge exchange ion temperature measurements using a single line of sight, which show good agreement with other ion temperature diagnostics. Building on these commissioning results and forward modelling of the system, a new observation geometry has been implemented for the next experimental campaign which will considerably improve the localisation of ion temperature and velocity profile measurements.