Integration of high confinement, high poloidal beta plasma with dual radiated power and detachment controls for divertor protection and ELM suppression
Abstract
Divertor detachment without serious core confinement quality loss in DIII-D’s high poloidal β scenario has been combined with impurity-induced ELM mitigation without disruption. Use of Ne previously granted access to a detached, non-ELMing regime that retained high confinement quality due to stimulation of Internal Transport Barrier (ITB) growth, but suffered from on-going core fuel dilution and high disruptivity. Excess Ne accumulation in the core plasma has now been avoided by feeding back core radiated power ($$P_{rad}$$) measurements to control Ne seeding, rather than using attachment fraction ($$A_{frac}$$) control with Ne; this also reduces disruptivity. At the same time, N2 seeding is used in a feedback loop with $$A_{frac}$$ measurements, which previously posed low disruption risk. In this way, the effect of Ne in the core is managed while avoiding excess seeding, and N2 acts to correct for any excess heat exhaust that might interfere with detachment. The average Ne flow rate was 38% of what was used in pure Ne $$A_{frac}$$ control, plus average N2 flow that was 43% of pure N2 $$A_{frac}$$ control, even while meeting an even deeper detachment target. Meanwhile, a steep pressure gradient in the core plasma reduces sensitivity to impurity-induced degradation of the pedestal and reasonable confinement quality was maintained despite operational challenges that blocked formation of an ITB in these experiments.
- Authors:
-
[1];
[3];
- General Atomics, San Diego, CA (United States)
- Chinese Academy of Sciences (CAS), Hefei (China)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sandia National Lab. (SNL-CA), Livermore, CA (United States)
- Publication Date:
- Research Org.:
- General Atomics, San Diego, CA (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES); National Natural Science Foundation of China (NSFC); National Magnetic Confinement Fusion Science Program of China
- OSTI Identifier:
- 1909380
- Alternate Identifier(s):
- OSTI ID: 2287656
- Report Number(s):
- DOE-GA-54698
Journal ID: ISSN 2352-1791; TRN: US2312117
- Grant/Contract Number:
- FC02-04ER54698; SC0010685; AC52-07NA27344; NA0003525; 11922513; 2017YFE0301300
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Nuclear Materials and Energy
- Additional Journal Information:
- Journal Volume: 34; Journal ID: ISSN 2352-1791
- Publisher:
- Elsevier
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Detachment; Control; Core-edge integration
Citation Formats
Eldon, D., Wang, H. Q., Wang, L., Ding, S., Garofalo, A. M., Gong, X. Z., McLean, A. G., Scotti, F., Watkins, J. G., and Weisberg, D. Integration of high confinement, high poloidal beta plasma with dual radiated power and detachment controls for divertor protection and ELM suppression. United States: N. p., 2022.
Web. doi:10.1016/j.nme.2022.101332.
Eldon, D., Wang, H. Q., Wang, L., Ding, S., Garofalo, A. M., Gong, X. Z., McLean, A. G., Scotti, F., Watkins, J. G., & Weisberg, D. Integration of high confinement, high poloidal beta plasma with dual radiated power and detachment controls for divertor protection and ELM suppression. United States. https://doi.org/10.1016/j.nme.2022.101332
Eldon, D., Wang, H. Q., Wang, L., Ding, S., Garofalo, A. M., Gong, X. Z., McLean, A. G., Scotti, F., Watkins, J. G., and Weisberg, D. Wed .
"Integration of high confinement, high poloidal beta plasma with dual radiated power and detachment controls for divertor protection and ELM suppression". United States. https://doi.org/10.1016/j.nme.2022.101332. https://www.osti.gov/servlets/purl/1909380.
@article{osti_1909380,
title = {Integration of high confinement, high poloidal beta plasma with dual radiated power and detachment controls for divertor protection and ELM suppression},
author = {Eldon, D. and Wang, H. Q. and Wang, L. and Ding, S. and Garofalo, A. M. and Gong, X. Z. and McLean, A. G. and Scotti, F. and Watkins, J. G. and Weisberg, D.},
abstractNote = {Divertor detachment without serious core confinement quality loss in DIII-D’s high poloidal β scenario has been combined with impurity-induced ELM mitigation without disruption. Use of Ne previously granted access to a detached, non-ELMing regime that retained high confinement quality due to stimulation of Internal Transport Barrier (ITB) growth, but suffered from on-going core fuel dilution and high disruptivity. Excess Ne accumulation in the core plasma has now been avoided by feeding back core radiated power ($P_{rad}$) measurements to control Ne seeding, rather than using attachment fraction ($A_{frac}$) control with Ne; this also reduces disruptivity. At the same time, N2 seeding is used in a feedback loop with $A_{frac}$ measurements, which previously posed low disruption risk. In this way, the effect of Ne in the core is managed while avoiding excess seeding, and N2 acts to correct for any excess heat exhaust that might interfere with detachment. The average Ne flow rate was 38% of what was used in pure Ne $A_{frac}$ control, plus average N2 flow that was 43% of pure N2 $A_{frac}$ control, even while meeting an even deeper detachment target. Meanwhile, a steep pressure gradient in the core plasma reduces sensitivity to impurity-induced degradation of the pedestal and reasonable confinement quality was maintained despite operational challenges that blocked formation of an ITB in these experiments.},
doi = {10.1016/j.nme.2022.101332},
journal = {Nuclear Materials and Energy},
number = ,
volume = 34,
place = {United States},
year = {Wed Dec 07 00:00:00 EST 2022},
month = {Wed Dec 07 00:00:00 EST 2022}
}
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