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Title: Stabilizing effect of resistivity towards ELM-free H-mode discharge in lithium-conditioned NSTX

Abstract

Linear stability analysis of the national spherical torus experiment (NSTX) Li-conditioned ELM-free H-mode equilibria is carried out in the context of the extended magneto-hydrodynamic (MHD) model in NIMROD. The purpose is to investigate the physical cause behind edge localized mode (ELM) suppression in experiment after the Li-coating of the divertor and the first wall of the NSTX tokamak. Besides ideal MHD modeling, including finite-Larmor radius effect and two-fluid Hall and electron diamagnetic drift contributions, a non-ideal resistivity model is employed, taking into account the increase of Z eff after Li-conditioning in ELM-free H-mode. Unlike an earlier conclusion from an eigenvalue code analysis of these equilibria, NIMROD results find that after reduced recycling from divertor plates, profile modification is necessary but insufficient to explain the mechanism behind complete ELMs suppression in ideal two-fluid MHD. After considering the higher plasma resistivity due to higher Z eff , the complete stabilization could be explained. A thorough analysis of both pre-lithium ELMy and with-lithium ELM-free cases using ideal and non-ideal MHD models is presented, after accurately including a vacuum-like cold halo region in NIMROD to investigate ELMs.

Authors:
; ; ORCiD logo
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Publication Date:
DOE Contract Number:  
AC02-09CH11466
Product Type:
Dataset
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; NSTX Lithium Stability Edge physics
Keywords:
NSTX Lithium Stability Edge physics
OSTI Identifier:
1367548
DOI:
10.11578/1367548

Citation Formats

Banerjee, D., Zhu, P., and Maingi, R. Stabilizing effect of resistivity towards ELM-free H-mode discharge in lithium-conditioned NSTX. United States: N. p., 2017. Web. doi:10.11578/1367548.
Banerjee, D., Zhu, P., & Maingi, R. Stabilizing effect of resistivity towards ELM-free H-mode discharge in lithium-conditioned NSTX. United States. doi:10.11578/1367548.
Banerjee, D., Zhu, P., and Maingi, R. 2017. "Stabilizing effect of resistivity towards ELM-free H-mode discharge in lithium-conditioned NSTX". United States. doi:10.11578/1367548. https://www.osti.gov/servlets/purl/1367548. Pub date:Sat Jul 01 00:00:00 EDT 2017
@article{osti_1367548,
title = {Stabilizing effect of resistivity towards ELM-free H-mode discharge in lithium-conditioned NSTX},
author = {Banerjee, D. and Zhu, P. and Maingi, R.},
abstractNote = {Linear stability analysis of the national spherical torus experiment (NSTX) Li-conditioned ELM-free H-mode equilibria is carried out in the context of the extended magneto-hydrodynamic (MHD) model in NIMROD. The purpose is to investigate the physical cause behind edge localized mode (ELM) suppression in experiment after the Li-coating of the divertor and the first wall of the NSTX tokamak. Besides ideal MHD modeling, including finite-Larmor radius effect and two-fluid Hall and electron diamagnetic drift contributions, a non-ideal resistivity model is employed, taking into account the increase of Z eff after Li-conditioning in ELM-free H-mode. Unlike an earlier conclusion from an eigenvalue code analysis of these equilibria, NIMROD results find that after reduced recycling from divertor plates, profile modification is necessary but insufficient to explain the mechanism behind complete ELMs suppression in ideal two-fluid MHD. After considering the higher plasma resistivity due to higher Z eff , the complete stabilization could be explained. A thorough analysis of both pre-lithium ELMy and with-lithium ELM-free cases using ideal and non-ideal MHD models is presented, after accurately including a vacuum-like cold halo region in NIMROD to investigate ELMs.},
doi = {10.11578/1367548},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2017},
month = {7}
}

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