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|Title:||Wall conditioning and ELM mitigation with boron nitride powder injection in KSTAR|
Supported in part by U.S. Dept. of Energy under contract DE- 61 AC02-09CH11466, in part the Ministry of Science, ICT and Future 62 Planning of the Republic of Korea through the Korean ITER Tech- 63 nology R&D Program (IN2010-3), in part by the R&D Program of 64 the KSTAR Experimental Collaboration and Fusion Plasma Research 65 (EN2101-12) through the Korea Institute of Fusion Energy (KFE), and 66 in part by the National R&D Program through the National Research 67 Foundation of Korea (NRF), funded by the Ministry of Science and ICT 68 (NRF-2019M1A7A1A03087560).
|Related Publication:||Gilson et al., 2021, Wall conditioning and ELM mitigation with boron nitride powder injection in KSTAR, Princeton Plasma Physics Laboratory, Princeton University DataSapce|
|Abstract:||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, 𝐼𝑝 = 500 kA, 𝐵𝑇 = 1.8 T, 𝑃NBI = 1.6 MW, and 𝑃ECH = 0.6 MW. Plasma densities were between 2 and 3 × 1019 m−3. In all cases, the pre-fill and startup gas-fueling was kept constant, suggesting that the decrease in baseline D𝛼 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.|
|Appears in Collections:||PPPL Collaborations|
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