U.S. Department of EnergyOffice of Scientific and Technical Information
Impact of lithium wall conditioning and wave-frequency on high density lower hybrid current drive experiment on EAST
Abstract
A series of dedicated lower hybrid current drive (LHCD) experiments on EAST shows that lithium wall conditioning extends LH current drive and heating up to the line-averaged density of n ̅_e≈ 4x1019 m-3 for both 2.45 and 4.6 GHz. Current drive at such a high density is crucial for the development of long-pulse non-inductive scenarios on EAST. With lithiation, the LH power injection of 1.5 MW at 2.45 GHz resulted in a drop of loop voltage of ~ 0.3 V, which is a comparable loop voltage drop observed with 1.1 MW at 4.6 GHz. The observed decrease in loop voltage is attributed mostly to the RF heating effect. Another LHCD experiment suggests that lithium wall coating has a more significant impact on the scrape-off-layer (SOL) properties than changes in the Greenwald fraction. LHCD at 2.45 GHz still suffers from a loss of efficiency. Enhanced power ionization in front of the launcher may cause the onset of density-dependent wave instabilities. The rise in the midplane SOL density may also accelerate a transition in the divertor regime, leading to additional ionization and collisional losses in the X-point divertor plasma. Ray-tracing modeling supports that a lower wave frequency is more prone to collisionalmore »
- Authors:
-
- OSTI
- Publication Date:
- DOE Contract Number:
- SC0010492
- Research Org.:
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center
- Sponsoring Org.:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY
- OSTI Identifier:
- 1889415
- DOI:
- https://doi.org/10.7910/DVN/OIXWJG
Citation Formats
Baek, S. G., Li, M. H., Wallace, G. M., Bonoli, P. T., Choi, W., Ding, B. J., Gao, W., Gong, X., Li, Y. C., Lin, S., Meng, L., Poli, F., Shiraiwa, S., Wang, M., Wang, Y. F., Wu, C. B., Yan, G. H., Wang, L., Zang, Q., and Zhao, H. Impact of lithium wall conditioning and wave-frequency on high density lower hybrid current drive experiment on EAST. United States: N. p., 2022.
Web. doi:10.7910/DVN/OIXWJG.
Baek, S. G., Li, M. H., Wallace, G. M., Bonoli, P. T., Choi, W., Ding, B. J., Gao, W., Gong, X., Li, Y. C., Lin, S., Meng, L., Poli, F., Shiraiwa, S., Wang, M., Wang, Y. F., Wu, C. B., Yan, G. H., Wang, L., Zang, Q., & Zhao, H. Impact of lithium wall conditioning and wave-frequency on high density lower hybrid current drive experiment on EAST. United States. doi:https://doi.org/10.7910/DVN/OIXWJG
Baek, S. G., Li, M. H., Wallace, G. M., Bonoli, P. T., Choi, W., Ding, B. J., Gao, W., Gong, X., Li, Y. C., Lin, S., Meng, L., Poli, F., Shiraiwa, S., Wang, M., Wang, Y. F., Wu, C. B., Yan, G. H., Wang, L., Zang, Q., and Zhao, H. 2022.
"Impact of lithium wall conditioning and wave-frequency on high density lower hybrid current drive experiment on EAST". United States. doi:https://doi.org/10.7910/DVN/OIXWJG. https://www.osti.gov/servlets/purl/1889415. Pub date:Tue Jun 21 00:00:00 EDT 2022
@article{osti_1889415,
title = {Impact of lithium wall conditioning and wave-frequency on high density lower hybrid current drive experiment on EAST},
author = {Baek, S. G. and Li, M. H. and Wallace, G. M. and Bonoli, P. T. and Choi, W. and Ding, B. J. and Gao, W. and Gong, X. and Li, Y. C. and Lin, S. and Meng, L. and Poli, F. and Shiraiwa, S. and Wang, M. and Wang, Y. F. and Wu, C. B. and Yan, G. H. and Wang, L. and Zang, Q. and Zhao, H.},
abstractNote = {A series of dedicated lower hybrid current drive (LHCD) experiments on EAST shows that lithium wall conditioning extends LH current drive and heating up to the line-averaged density of n ̅_e≈ 4x1019 m-3 for both 2.45 and 4.6 GHz. Current drive at such a high density is crucial for the development of long-pulse non-inductive scenarios on EAST. With lithiation, the LH power injection of 1.5 MW at 2.45 GHz resulted in a drop of loop voltage of ~ 0.3 V, which is a comparable loop voltage drop observed with 1.1 MW at 4.6 GHz. The observed decrease in loop voltage is attributed mostly to the RF heating effect. Another LHCD experiment suggests that lithium wall coating has a more significant impact on the scrape-off-layer (SOL) properties than changes in the Greenwald fraction. LHCD at 2.45 GHz still suffers from a loss of efficiency. Enhanced power ionization in front of the launcher may cause the onset of density-dependent wave instabilities. The rise in the midplane SOL density may also accelerate a transition in the divertor regime, leading to additional ionization and collisional losses in the X-point divertor plasma. Ray-tracing modeling supports that a lower wave frequency is more prone to collisional power loss. The experiments confirm that lithiation is a useful tool to control the SOL plasma, and suggest that density control in front of the launcher may be critical to mitigating power loss mechanisms in the plasma boundary.},
doi = {10.7910/DVN/OIXWJG},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Jun 21 00:00:00 EDT 2022},
month = {Tue Jun 21 00:00:00 EDT 2022}
}