Progress Toward Divertor Detachment in TCV H-mode Discharges

Progress Toward Divertor Detachment in TCV H-mode Discharges

Progress Toward Divertor Detachment in TCV H-mode Discharges 150 150 UKAEA Opendata

Recent experiments on TCV have made significant progress toward partial detachment of the outer divertor in neutral beam heated H-mode plasmas. The heating power required to enter H-mode was measured in a range of divertor configurations, finding that, in the vicinity of the PL-H/ne curve, the threshold power is largely independent of the poloidal flux expansion or major radius of the outer divertor, and in the snowflake minus configuration. In ELM-free scenarios, fuelling and nitrogen seeding was used to cool the divertor sufficiently to achieve a factor 2 reduction in the total divertor power load, but no significant reduction in the total divertor particle load was observed. ELM-free scenarios were used to study the impact of outer divertor poloidal flux expansion on divertor cooling, finding it does not have a significant effect. Experiments in ELMy H-mode experiments using nitrogen seeding were able to achieve a factor 2 reduction in the outer divertor power load and a ~30% reduction in the particle flux. The influence of outer target major radius on divertor cooling in ELMy H-mode experiments studied divertor cooling with the strike point placed at R = 0.75m and 1.03m, finding that the movement of the impurity emission front, a proxy for divertor cooling, was ~20% slower when the strike point is placed at larger major radius.

Collection:
Journals
Journal:
Plasma Physics and Controlled Fusion
Publisher:
IOP (Institute of Physics)
Published date:
10/04/2021