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Title: The role of MHD in 3D aspects of massive gas injection

Simulations of massive gas injection for disruption mitigation in DIII-D are carried out to compare the toroidal peaking of radiated power for the cases of one and two gas jets. The radiation toroidal peaking factor (TPF) results from a combination of the distribution of impurities and the distribution of heat flux associated with the n = 1 mode. When we ignored the effects of strong uni-directional neutral beam injection and rotation present in the experiment, the injected impurities were found to spread helically along field lines preferentially toward the high-field-side, which is explained in terms of a nozzle equation. Thus when considering the plasma rest frame, reversing the current direction also reverses the toroidal direction of impurity spreading. During the pre-thermal quench phase of the disruption, the toroidal peaking of radiated power is reduced in a straightforward manner by increasing from one to two gas jets. But, during the thermal quench phase, reduction in the TPF is achieved only for a particular arrangement of the two gas valves with respect to the field line pitch. Particularly, the relationship between the two valve locations and the 1/1 mode phase is critical, where gas valve spacing that is coherent with 1/1 symmetrymore » effectively reduces TPF.« less
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [1] ;  [3] ;  [4] ;  [3] ;  [5] ;  [1] ;  [3] ;  [6] ;  [2]
  1. Univ. of California San Diego, La Jolla, CA (United States)
  2. General Atomics, San Diego, CA (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  4. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  5. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  6. Univ. of Washington, Seattle, WA (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; FG02-95ER54309; FC02-04ER54698; FG02-07ER54917; FC02-99ER54512; AC52-07NA27344; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 55; Journal Issue: 7; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of California, San Diego, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24); USDOE Advanced Research Projects Agency - Energy (ARPA-E); USDOE Office of Nuclear Energy (NE)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; tokamaks; resistive MHD modes; magnetohydrodynamic; disruption mitigation; DIII-D; PELLET
OSTI Identifier:
1295126
Alternate Identifier(s):
OSTI ID: 1238916; OSTI ID: 1353091

Izzo, Valerie A., Parks, P. B., Eidietis, Nicholas W., Shiraki, Daisuke, Hollmann, Eric M., Commaux, Nicolas, Granetz, Robert S., Humphreys, David A., Lasnier, Charles J., Moyer, Richard A., Paz-Soldan, C., Raman, R., and Strait, E. J.. The role of MHD in 3D aspects of massive gas injection. United States: N. p., Web. doi:10.1088/0029-5515/55/7/073032.
Izzo, Valerie A., Parks, P. B., Eidietis, Nicholas W., Shiraki, Daisuke, Hollmann, Eric M., Commaux, Nicolas, Granetz, Robert S., Humphreys, David A., Lasnier, Charles J., Moyer, Richard A., Paz-Soldan, C., Raman, R., & Strait, E. J.. The role of MHD in 3D aspects of massive gas injection. United States. doi:10.1088/0029-5515/55/7/073032.
Izzo, Valerie A., Parks, P. B., Eidietis, Nicholas W., Shiraki, Daisuke, Hollmann, Eric M., Commaux, Nicolas, Granetz, Robert S., Humphreys, David A., Lasnier, Charles J., Moyer, Richard A., Paz-Soldan, C., Raman, R., and Strait, E. J.. 2015. "The role of MHD in 3D aspects of massive gas injection". United States. doi:10.1088/0029-5515/55/7/073032. https://www.osti.gov/servlets/purl/1295126.
@article{osti_1295126,
title = {The role of MHD in 3D aspects of massive gas injection},
author = {Izzo, Valerie A. and Parks, P. B. and Eidietis, Nicholas W. and Shiraki, Daisuke and Hollmann, Eric M. and Commaux, Nicolas and Granetz, Robert S. and Humphreys, David A. and Lasnier, Charles J. and Moyer, Richard A. and Paz-Soldan, C. and Raman, R. and Strait, E. J.},
abstractNote = {Simulations of massive gas injection for disruption mitigation in DIII-D are carried out to compare the toroidal peaking of radiated power for the cases of one and two gas jets. The radiation toroidal peaking factor (TPF) results from a combination of the distribution of impurities and the distribution of heat flux associated with the n = 1 mode. When we ignored the effects of strong uni-directional neutral beam injection and rotation present in the experiment, the injected impurities were found to spread helically along field lines preferentially toward the high-field-side, which is explained in terms of a nozzle equation. Thus when considering the plasma rest frame, reversing the current direction also reverses the toroidal direction of impurity spreading. During the pre-thermal quench phase of the disruption, the toroidal peaking of radiated power is reduced in a straightforward manner by increasing from one to two gas jets. But, during the thermal quench phase, reduction in the TPF is achieved only for a particular arrangement of the two gas valves with respect to the field line pitch. Particularly, the relationship between the two valve locations and the 1/1 mode phase is critical, where gas valve spacing that is coherent with 1/1 symmetry effectively reduces TPF.},
doi = {10.1088/0029-5515/55/7/073032},
journal = {Nuclear Fusion},
number = 7,
volume = 55,
place = {United States},
year = {2015},
month = {6}
}