Comparison between MAST-U conventional and Super-X configurations through SOLPS-ITER modelling

TY - JOUR

T1 - Comparison between MAST-U conventional and Super-X configurations through SOLPS-ITER modelling

AU - Fil, Alexandre

AU - Lipschultz, Bruce

AU - Moulton, David

AU - Thornton, A J

AU - Dudson, Ben D

AU - Myatra, Omkar

AU - Verhaegh, Kevin

N1 - © 2022 Crown copyright.

PY - 2022/8/12

Y1 - 2022/8/12

N2 - MAST-U has recently started operating with a Super-X divertor, designed to increase total flux expansion and neutral trapping, both predicted through simple analytic models and SOLPS calculations to reduce the plasma and impurity density detachment thresholds. In this study, utilising the SOLPS-ITER code, we are quantifying the possible gain allowed by the MAST-U Super-X and neutral baffling geometry, in terms of access to detachment. We show that a significant reduction of the upstream density detachment threshold (up to a factor 1.6) could be achieved in MAST-U, for the Super-X, as opposed to conventional divertor geometry, mainly through an increased total flux expansion, neutral trapping being found very similar between the different configurations. We also show that variations of the strike-point angle are complex to interpret in such a tightly baffled geometry, and that a case in which the target normal points more towards the separatrix does not necessarily imply a lower detachment threshold. As in previous calculations for TCV, we quantify the role of neutral effects through developing and applying a quantitative definition of neutral trapping.

AB - MAST-U has recently started operating with a Super-X divertor, designed to increase total flux expansion and neutral trapping, both predicted through simple analytic models and SOLPS calculations to reduce the plasma and impurity density detachment thresholds. In this study, utilising the SOLPS-ITER code, we are quantifying the possible gain allowed by the MAST-U Super-X and neutral baffling geometry, in terms of access to detachment. We show that a significant reduction of the upstream density detachment threshold (up to a factor 1.6) could be achieved in MAST-U, for the Super-X, as opposed to conventional divertor geometry, mainly through an increased total flux expansion, neutral trapping being found very similar between the different configurations. We also show that variations of the strike-point angle are complex to interpret in such a tightly baffled geometry, and that a case in which the target normal points more towards the separatrix does not necessarily imply a lower detachment threshold. As in previous calculations for TCV, we quantify the role of neutral effects through developing and applying a quantitative definition of neutral trapping.

U2 - 10.1088/1741-4326/ac81d8

DO - 10.1088/1741-4326/ac81d8

M3 - Article

SN - 0029-5515

VL - 62

JO - Nuclear Fusion

JF - Nuclear Fusion

M1 - 096026

ER -