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

Gilson, Erik ; Lee, H.; Bortolon, A. ; Choe, W.; Diallo, A. ; Hong, S. H.; Lee, H. M.; Maingi, R. ; Mansfield, D. K. ; Nagy, A. ; Park, S. H.; Song, I. W.; Song, J. I.; Yun, S. W.; Yoon, S. W.; Nazikian, R.
Issue date: 2021
Creative Commons Attribution 4.0 International (CC BY)
Cite as:
Gilson, Erik, Lee, H., Bortolon, A., Choe, W., Diallo, A., Hong, S. H., Lee, H. M., Maingi, R., Mansfield, D. K., Nagy, A., Park, S. H., Song, I. W., Song, J. I., Yun, S. W., Yoon, S. W., & Nazikian, R. (2021). Wall conditioning and ELM mitigation with boron nitride powder injection in KSTAR [Data set]. Princeton Plasma Physics Laboratory, Princeton University. https://doi.org/10.11578/1888253
  author      = {Gilson, Erik and
                Lee, H. and
                Bortolon, A. and
                Choe, W. and
                Diallo, A. and
                Hong, S. H. and
                Lee, H. M. and
                Maingi, R. and
                Mansfield, D. K. and
                Nagy, A. and
                Park, S. H. and
                Song, I. W. and
                Song, J. I. and
                Yun, S. W. and
                Yoon, S. W. and
                Nazikian, R.},
  title       = {{Wall conditioning and ELM mitigation wit
                h boron nitride powder injection in KSTA
  publisher   = {{Princeton Plasma Physics Laboratory, Pri
                nceton University}},
  year        = 2021,
  url         = {https://doi.org/10.11578/1888253}

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, 𝐡𝑇 = 1.8 T, 𝑃NBI = 1.6 MW, and 𝑃ECH = 0.6 MW. Plasma densities were between 2 and 3 Γ— 1019 mβˆ’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.

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1 Fig.3.README.txt 174 Bytes
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