Wall conditioning and ELM mitigation with boron nitride powder injection in KSTAR

Journal Article · Mon Jul 19 00:00:00 EDT 2021 · Nuclear Materials and Energy

DOI:https://doi.org/10.1016/j.nme.2021.101043· OSTI ID:1822213

Gilson, E. P. ^[1]; Lee, H. H. ^[2]; Bortolon, A. ^[1]; Choe, W. ^[3]; Diallo, A. ^[1]; Hong, S. H. ^[2]; Lee, H. M. ^[2]; Lee, J. ^[4]; Maingi, R. ^[1]; Mansfield, D. K. ^[1]; Nagy, A. ^[1]; Park, S. H. ^[2]; Song, I. W. ^[3]; Song, J. I. ^[2]; Yun, S. W. ^[2]; Yoon, S. W. ^[2]; Nazikian, R. ^[1]

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1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
2. Korea Institute of Fusion Energy, Yuseong-gu, Daejeon (Korea, Republic of)
3. Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon (Korea, Republic of)
4. Korea University of Science and Technology, Yuseong-gu, Daejeon (Korea, Republic of)

Results from KSTAR powder injection experiments, in which tens of milligrams of boron nitride (BN) were dropped into low-power H-mode plasmas, show an improvement in wall conditions in subsequent discharges and, in some cases, a reduction or elimination of edge-localized modes (ELMs). Injected powder is distributed by the plasma flow and is deposited on the wall and, over the course of several discharges, was observed to gradually reduce recycling by 33%, and decrease both the ELM amplitude and frequency. This is the first demonstration of the use of BN for ELM mitigation. In all of these experiments, an Impurity Powder Dropper (IPD) was used to introduce precise, controllable amounts of the materials into ELMy H-mode KSTAR discharges. The plasma duration was between 10 s and 15 s, $I_p=500$ kA, $B_T=1.8$ T, $P_{\mathrm{NBI}}=1.6$ MW, and $P_{\mathrm{ECH}}=0.6$ MW. Plasma densities were between 2 and $3\times 10^{19}$ m^-3. In all cases, the pre-fill and startup gas-fueling was kept constant, suggesting that the decrease in baseline D ${}_{\alpha }$ emission is in fact due to a reduction in recycling. The results presented herein highlight the viability of powder injection for intra-shot and between-shot wall conditioning

• Research Organization: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
• Sponsoring Organization: Ministry of Science, ICT and Future Planning of the Republic of Korea; USDOE
• Grant/Contract Number: AC02-09CH11466
• OSTI ID: 1822213
• Journal Information: Nuclear Materials and Energy, Journal Name: Nuclear Materials and Energy Vol. 28; ISSN 2352-1791
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
Boron nitride
ELM
Edge-localized mode
Impurity
Wall conditioning