Simulations of divertor designs that spatially separate power and particle exhaust using mid-leg divertor particle pumping

Yu, Jonathan H.; Wilcox, Robert S.; Maurizio, Roberto; Holm, Andreas; Allen, S. L.; Choi, Wilkie; Fenstermacher, M. E.; Groth, Mathias; Leonard, A. W.; McLean, A. G.; Scotti, Filippo; Shafer, Morgan W.

doi:10.1016/j.nme.2024.101826

Title: Simulations of divertor designs that spatially separate power and particle exhaust using mid-leg divertor particle pumping

Journal Article · 27 November 2024 · Nuclear Materials and Energy

DOI: https://doi.org/10.1016/j.nme.2024.101826 · OSTI ID:2480563

Yu, Jonathan H. ^[1];

^[2];

^[1]; Holm, Andreas ^[3]; Allen, S. L. ^[3]; Choi, Wilkie ^[1]; Fenstermacher, M. E. ^[3]; Groth, Mathias ^[4]; Leonard, A. W. ^[1]; McLean, A. G. ^[3]; Scotti, Filippo ^[3];

^[2]

General Atomics, San Diego, CA (United States)
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
Aalto University, Espoo (Finland)

Predictive design modeling of a Dissipation-Focused Divertor for future operation in DIII-D reveals that increasing the poloidal distance of the pump duct entrance from the target surface along the low-field side divertor baffle increases neutral compression and modifies the spatial distribution of power dissipation. With a divertor pump located mid-leg between the target and the X-point, SOLPS-ITER boundary plasma simulations without drifts predict the formation of a dense neutral cloud near the target with > 30x higher neutral compression in detachment, a more stable detachment front located further from the target, and ~25% lower outer midplane separatrix density required for detachment onset, compared to a pump located in the scrape-off layer at the target surface. Up to 19 MW of power flowing into the divertors is modeled using the following two numerical implementations for particle pumping: a specified fraction of particles incident on variable wall sections of the plasma grid is removed from the computational domain (so-called albedo pumping), and a pump duct is modeled which includes dynamics of kinetic neutrals in the duct. The simulations show that the detachment front is located between the divertor target and the X-point and is relatively stable near the pump entrance, without a strong dependence on gas puff rate or injected power. The mid-leg pump design spatially separates the two primary functions of a divertor (power handling and particle exhaust), with the majority of power dissipation occurring near the target plate and particle exhaust taking place further upstream. The benefit of enhanced dissipation using mid-leg pumping comes at the cost of a higher outer midplane separatrix density for a given amount of particle injection.

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Research Organization:: General Atomics, San Diego, CA (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Organization:: USDOE Office of Science (SC), Fusion Energy Sciences (FES)

Grant/Contract Number:: FC02-04ER54698; AC52-07NA27344; AC05-00OR22725

OSTI ID:: 2480563

Journal Information:: Nuclear Materials and Energy, Journal Name: Nuclear Materials and Energy Vol. 41; ISSN 2352-1791

Publisher:: ElsevierCopyright Statement

Country of Publication:: United States

Language:: English

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Title: Simulations of divertor designs that spatially separate power and particle exhaust using mid-leg divertor particle pumping

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