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Title: On detachment asymmetry and stability

Abstract

Three issues related to the physics of divertor detachment are analyzed in detail: the criteria for the onset of complete divertor detachment, the role of neutrals in “symmetryzation” of detachment in the inner and outer divertors, and the transition to divertor detachment. The results of comprehensive 2D numerical simulations with the SOLPS4.3 package are compared with some experimental data and predictions based on simplified analytical models. It is shown that it is the ratio of the upstream plasma pressure to the specific power flux entering the recycling region that controls the local onset of detachment on a specific flux tube. Pup/qreclycl≥(Pup/qreclycl)crit remains the valid criterion also in the presence of seeded impurity, if the impurity radiation and hydrogen recycling regions are spatially separated. Detailed analysis indicates that the reverse plasma flow forming on the most heat loaded flux tubes in the outer divertor under the influence of the neutrals coming from the deeply detached inner divertor plays the key role in the detachment “symmetryzation” and allows the outer divertor to reach the detached regime. Finally, it is demonstrated that a gradual increase of the perpendicular heat transport in the edge plasma during transition to the detached regime can make thismore » transition bifurcation-like.« less

Authors:
ORCiD logo [1]; ORCiD logo [1];  [2]
+ Show Author Affiliations
  1. National Research Centre (NRC), Moscow (Russian Federation). Kurchatov Inst. (NRCKI); National Research Nuclear Univ., Moscow (Russian Federation)
  2. National Research Nuclear Univ., Moscow (Russian Federation); Univ. of California, San Diego, CA (United States). Dept. of Physics
Publication Date:
Research Org.:
Univ. of California, San Diego, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1535324
Alternate Identifier(s):
OSTI ID: 1368605
Grant/Contract Number:  
FG02-04ER54739
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 7; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Physics

Citation Formats

Pshenov, A. A., Kukushkin, A. S., and Krasheninnikov, S. I. On detachment asymmetry and stability. United States: N. p., 2017. Web. doi:10.1063/1.4991402.
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Pshenov, A. A., Kukushkin, A. S., & Krasheninnikov, S. I. On detachment asymmetry and stability. United States. doi:10.1063/1.4991402.
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Pshenov, A. A., Kukushkin, A. S., and Krasheninnikov, S. I. Fri . "On detachment asymmetry and stability". United States. doi:10.1063/1.4991402. https://www.osti.gov/servlets/purl/1535324.
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@article{osti_1535324,
title = {On detachment asymmetry and stability},
author = {Pshenov, A. A. and Kukushkin, A. S. and Krasheninnikov, S. I.},
abstractNote = {Three issues related to the physics of divertor detachment are analyzed in detail: the criteria for the onset of complete divertor detachment, the role of neutrals in “symmetryzation” of detachment in the inner and outer divertors, and the transition to divertor detachment. The results of comprehensive 2D numerical simulations with the SOLPS4.3 package are compared with some experimental data and predictions based on simplified analytical models. It is shown that it is the ratio of the upstream plasma pressure to the specific power flux entering the recycling region that controls the local onset of detachment on a specific flux tube. Pup/qreclycl≥(Pup/qreclycl)crit remains the valid criterion also in the presence of seeded impurity, if the impurity radiation and hydrogen recycling regions are spatially separated. Detailed analysis indicates that the reverse plasma flow forming on the most heat loaded flux tubes in the outer divertor under the influence of the neutrals coming from the deeply detached inner divertor plays the key role in the detachment “symmetryzation” and allows the outer divertor to reach the detached regime. Finally, it is demonstrated that a gradual increase of the perpendicular heat transport in the edge plasma during transition to the detached regime can make this transition bifurcation-like.},
doi = {10.1063/1.4991402},
journal = {Physics of Plasmas},
number = 7,
volume = 24,
place = {United States},
year = {2017},
month = {7}
}
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DOI:  10.1063/1.4991402
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