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Title: Influence of the inverse sheath on divertor plasma performance in tokamak edge plasma simulations

Abstract

Recently, it was shown that strong electron thermionic emission from material walls could result in the formation of an “inverse sheath”, which prevents the flow of cold ions to the wall. Such regimes look very favorably from the point of view of plasma-material interactions at the edge of magnetic fusion devices, where the problem of the erosion of plasma facing components under ion irradiation is one of the key issues for developing of future magnetic fusion reactors. However, it is not clear whether such regimes are compatible with edge plasma parameters and heat removal requirements in fusion reactors.To address the issue of practicality of the “inverse sheath” regime for edge tokamak plasma conditions, we perform a set of numerical simulations with 2D edge plasma transport code UEDGE for a DIII-D-like geometry and magnetic configuration.To describe both “standard” and “inverse sheath” conditions within the framework of the UEDGE code (which does not consider the sheath region per se), at the material surfaces, we apply effective boundary conditions which emulate both “standard” and“inverse sheath” regimes. We demonstrate that for the same input parameters, spatial distributions of edge plasma parameters corresponding to detached divertor and“inverse sheath” regimes are similar, with only a fewmore » minor differences. We discuss the compatibility of “inverse sheath” regimes with core plasma parameters.« less

Authors:
 [1];  [1];  [1]
  1. Univ. of California, San Diego, CA (United States)
Publication Date:
Research Org.:
Univ. of California, San Diego, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1603139
Alternate Identifier(s):
OSTI ID: 1580609
Grant/Contract Number:  
FG02-04ER54739
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Contributions to Plasma Physics
Additional Journal Information:
Journal Volume: 60; Journal Issue: 5-6; Journal ID: ISSN 0863-1042
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Masline, Rebecca, Smirnov, Roman D., and Krasheninnikov, Sergei I. Influence of the inverse sheath on divertor plasma performance in tokamak edge plasma simulations. United States: N. p., 2019. Web. doi:10.1002/ctpp.201900097.
Masline, Rebecca, Smirnov, Roman D., & Krasheninnikov, Sergei I. Influence of the inverse sheath on divertor plasma performance in tokamak edge plasma simulations. United States. doi:10.1002/ctpp.201900097.
Masline, Rebecca, Smirnov, Roman D., and Krasheninnikov, Sergei I. Sat . "Influence of the inverse sheath on divertor plasma performance in tokamak edge plasma simulations". United States. doi:10.1002/ctpp.201900097.
@article{osti_1603139,
title = {Influence of the inverse sheath on divertor plasma performance in tokamak edge plasma simulations},
author = {Masline, Rebecca and Smirnov, Roman D. and Krasheninnikov, Sergei I.},
abstractNote = {Recently, it was shown that strong electron thermionic emission from material walls could result in the formation of an “inverse sheath”, which prevents the flow of cold ions to the wall. Such regimes look very favorably from the point of view of plasma-material interactions at the edge of magnetic fusion devices, where the problem of the erosion of plasma facing components under ion irradiation is one of the key issues for developing of future magnetic fusion reactors. However, it is not clear whether such regimes are compatible with edge plasma parameters and heat removal requirements in fusion reactors.To address the issue of practicality of the “inverse sheath” regime for edge tokamak plasma conditions, we perform a set of numerical simulations with 2D edge plasma transport code UEDGE for a DIII-D-like geometry and magnetic configuration.To describe both “standard” and “inverse sheath” conditions within the framework of the UEDGE code (which does not consider the sheath region per se), at the material surfaces, we apply effective boundary conditions which emulate both “standard” and“inverse sheath” regimes. We demonstrate that for the same input parameters, spatial distributions of edge plasma parameters corresponding to detached divertor and“inverse sheath” regimes are similar, with only a few minor differences. We discuss the compatibility of “inverse sheath” regimes with core plasma parameters.},
doi = {10.1002/ctpp.201900097},
journal = {Contributions to Plasma Physics},
issn = {0863-1042},
number = 5-6,
volume = 60,
place = {United States},
year = {2019},
month = {12}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on December 28, 2020
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Works referenced in this record:

Thermionic Cooling of the Target Plasma to a Sub-eV Temperature
journal, January 2019


Strongly Emitting Surfaces Unable to Float below Plasma Potential
journal, February 2016


Physics of ultimate detachment of a tokamak divertor plasma
journal, September 2017


Negative plasma potential relative to electron-emitting surfaces
journal, September 2013


Plasma-material interactions in current tokamaks and their implications for next step fusion reactors
journal, December 2001