Speaker
Description
Demonstrating robust control of power and particle exhaust is one of the major challenges the first generation of power plant scale fusion devices will face. In the pursuit of core-divertor integrated operating scenarios, improving access to, and stability of detachment using impurity seeding in advanced divertor configurations shows significant promise [2].
MAST Upgrade has demonstrated improvements in facilitating detachment, as well as reduced sensitivity of the detachment front location to control parameters in its Super-X divertor (SXD) over the conventional divertor configuration in both experiments and modelling [3, 4, 5]. Spectroscopic studies have shown that its tight baffles plug neutrals in the divertor, achieving deep detachment in SXD by increasing plasma-neutral interaction [6].
We compare the exhaust performance of N2 seeded and divertor D2 fuelled H-mode plasma discharges with maximal NBI heating power (3.2 MW) in double-null SXD configuration from MAST Upgrade’s latest experimental campaign. We analyse differences in degree of detachment, examining changes to pressure and power losses at increasing rates of N2 and D2 injection. Thus, we aim to better understand the role that impurity seeding and divertor fuelling play in widening the detachment window.
Using spectroscopic reconstructions of atomic and molecular ineractions, we show that for similar upstream conditions and detachment front locations D2 puffing generates lower temperatures in SXD than N2 seeding, as the latter considerably undermines hydrogenic power loss processes.
This work is supported by the Engineering and Physical Sciences Research Council [grant number 2928960].
References:
[1] See author list of J. Harrison et al. 2019 Nucl. Fusion 59 112011
[2] V. A. Soukhanovskii 2017 Plasma Phys. Control. Fusion 59 064005
[3] J. R. Harrison et al 2024 Plasma Phys. Control. Fusion 66 065019
[4] D. Moulton et al 2024 Nucl. Fusion 64 076049
[5] O. Myatra et al 2023 Nucl. Fusion 63 096018
[6] K. Verhaegh et al 2023 Nucl. Fusion 63 016014