Initial Fulcher band observations from high resolution spectroscopy in the MAST-U divertor


Osborne, N ORCID: 0000-0002-3773-6113, Verhaegh, K ORCID: 0000-0002-0500-2764, Bowden, MD ORCID: 0000-0003-4128-4823, Wijkamp, T ORCID: 0000-0003-3110-8682, Lonigro, N ORCID: 0000-0001-8581-0384, Ryan, P, Pawelec, E ORCID: 0000-0003-1333-6331, Lipschultz, B ORCID: 0000-0001-5968-3684, Soukhanovskii, V ORCID: 0000-0001-5519-0145 and van den Biggelaar, T (2024) Initial Fulcher band observations from high resolution spectroscopy in the MAST-U divertor Plasma Physics and Controlled Fusion, 66 (2). 025008-025008. ISSN 0741-3335, 1361-6587

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Abstract

Abstract High resolution D 2 ∗ Fulcher band spectroscopy was used in the MAST-U divertors during Super-X and (shorter-legged) elongated divertor density ramps with D 2 fuelling from the mid-plane high-field side. In the Super-X case, the upper divertor showed ground state rotational temperatures of the D 2 molecules increasing from ~6000 K, starting at the detachment onset, to ~9000 K during deepening detachment. This was correlated with the movement of the Fulcher emission region towards the X-point, which is in turn correlated with the movement of the ionisation source. The increase in rotational temperature occurred throughout the divertor except near the divertor entrance, where ionisation was still the dominant process. Qualitative agreement was obtained between the lower and upper divertor. Similar rotational temperatures were obtained in the elongated divertor before the detachment onset, although the increase in rotational temperature during detachment was less clearly observed as less deep detachment was obtained. The measured vibrational distribution of the upper Fulcher state does not agree with a ground state Boltzmann distribution but shows a characteristically elevated population in the ν  = 2 and ν  = 3 bands in particular; which is strongly correlated to the rotational temperature.

Item Type: Article
Uncontrolled Keywords: 5102 Atomic, Molecular and Optical Physics, 51 Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 16 Jul 2024 13:58
Last Modified: 21 Nov 2025 14:55
DOI: 10.1088/1361-6587/ad1654
Open Access URL: https://iopscience.iop.org/article/10.1088/1361-65...
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3182937
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