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Title: Center for Extended Magnetohydrodrynamic Modeling

Abstract

This work used the NIMROD code to solve two tokamak regimes found on the DIII-D tokamak. The first regime studied is the Quiescent H-mode regime that has the advantage of enabling tokamak high performance without the deleterious effects of Edge Localized Modes (ELMs). ELMs are a possible impediment to the success of tokamaks as a burning plasma reactor and the QH mode regime provides a mechanism for avoiding it. The QH mode achieves this state due to the appearance of long wavelength instability that saturates instead of reaching an ELM state. NIMROD simulations were able to describe many of the features of a particular discharge, including the importance of shear flow in reaching the state, the role of the parallel heat flux to decorrelate the temperature and velocity fluctations, and in the correlation of density and velocity fluctations to provide the density pumpout. This work resulted in two direct publications and an invited talk. Progress towards these publications resulted in two more publications (verification and solving the Grad-Shafranov equation with scrape-off-layer currents). The second regime studied was the Giant Sawtooth regime whereby energetic particles affect the stability of the 1/1 mode. This work resulted in performance improvements of NIMROD's energeticmore » particle algorithms, and improvements to the drift-kinetic equation infrastructure used by both continuum and energetic particle closure methods. The studies proved more computationally demanding than expected because as the 1/1 is stabilized, the near marginal conditions cause long simulations times. Publication of this work is in progress under other funding.« less

Authors:
 [1]
  1. Tech-X Corporation, Boulder, CO (United States)
Publication Date:
Research Org.:
Tech-X Corporation, Boulder, CO (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
OSTI Identifier:
1437376
DOE Contract Number:  
FC02-08ER54972
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; plasma physics; fusion; tokamak; computational plasma physics; theoretical plasma physics

Citation Formats

Kruger, Scott E. Center for Extended Magnetohydrodrynamic Modeling. United States: N. p., 2018. Web. doi:10.2172/1437376.
Kruger, Scott E. Center for Extended Magnetohydrodrynamic Modeling. United States. doi:10.2172/1437376.
Kruger, Scott E. Tue . "Center for Extended Magnetohydrodrynamic Modeling". United States. doi:10.2172/1437376. https://www.osti.gov/servlets/purl/1437376.
@article{osti_1437376,
title = {Center for Extended Magnetohydrodrynamic Modeling},
author = {Kruger, Scott E.},
abstractNote = {This work used the NIMROD code to solve two tokamak regimes found on the DIII-D tokamak. The first regime studied is the Quiescent H-mode regime that has the advantage of enabling tokamak high performance without the deleterious effects of Edge Localized Modes (ELMs). ELMs are a possible impediment to the success of tokamaks as a burning plasma reactor and the QH mode regime provides a mechanism for avoiding it. The QH mode achieves this state due to the appearance of long wavelength instability that saturates instead of reaching an ELM state. NIMROD simulations were able to describe many of the features of a particular discharge, including the importance of shear flow in reaching the state, the role of the parallel heat flux to decorrelate the temperature and velocity fluctations, and in the correlation of density and velocity fluctations to provide the density pumpout. This work resulted in two direct publications and an invited talk. Progress towards these publications resulted in two more publications (verification and solving the Grad-Shafranov equation with scrape-off-layer currents). The second regime studied was the Giant Sawtooth regime whereby energetic particles affect the stability of the 1/1 mode. This work resulted in performance improvements of NIMROD's energetic particle algorithms, and improvements to the drift-kinetic equation infrastructure used by both continuum and energetic particle closure methods. The studies proved more computationally demanding than expected because as the 1/1 is stabilized, the near marginal conditions cause long simulations times. Publication of this work is in progress under other funding.},
doi = {10.2172/1437376},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2018},
month = {5}
}