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Title: Radiation asymmetries during disruptions on DIII-D caused by massive gas injectiona)

Abstract

One of the major challenges that the ITER tokamak will have to face during its operations are disruptions. During the last few years, it has been proven that the global consequences of a disruption can be mitigated by the injection of large quantities of impurities. But one aspect that has been difficult to study was the possibility of local effects inside the torus during such injection that could damage a portion of the device despite the global heat losses and generated currents remaining below design parameter. 3D MHD simulations show that there is a potential for large toroidal asymmetries of the radiated power during impurity injection due to the interaction between the particle injection plume and a large n=1 mode. Another aspect of 3D effects is the potential occurrence of Vertical Displacement Events (VDE), which could induce large poloidal heat load asymmetries. This potential deleterious effect of 3D phenomena has been studied on the DIII-D tokamak thanks to the implementation of a multi-location massive gas injection (MGI) system as well as new diagnostic capabilities. This study showed the existence of a correlation between the location of the n=1 mode and the local heat load on the plasma facing components butmore » shows also that this effect is much smaller than anticipated (peaking factor of ~1.1 vs 3-4 according to the simulations). There seems to be no observable heat load on the first wall of DIII-D at the location of the impurity injection port as well as no significant radiation asymmetries whether one or 2 valves are fired. This study enabled the first attempt of mitigation of a VDE using impurity injection at different poloidal locations. The results showed a more favorable heat deposition when the VDE is mitigated early (right at the onset) by impurity injection. As a result, no significant improvement of the heat load mitigation efficiency has been observed for late particle injection whether the injection is done “in the way” of the VDE (upward VDE mitigated by injection from the upper part of the vessel vs the lower part) or not.« less

Authors:
 [1];  [1];  [1];  [2];  [3];  [3];  [2];  [3];  [4];  [2];  [3];  [1];  [1];  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Univ. of California San Diego, San Diego, CA (United States)
  3. General Atomics, San Diego, CA (United States)
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA); USDOE Office of Nuclear Energy (NE)
OSTI Identifier:
1542704
Alternate Identifier(s):
OSTI ID: 1223598; OSTI ID: 1345230
Report Number(s):
LLNL-JRNL-752015
Journal ID: ISSN 1070-664X; PHPAEN; 895371
Grant/Contract Number:  
AC52-07NA27344; AC05-00OR22725; FC02-04ER54698; FG02-07ER54917
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 21; Journal Issue: 10; 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; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS

Citation Formats

Commaux, N., Baylor, L. R., Jernigan, T. C., Hollmann, E. M., Humphreys, D. A., Wesley, J. C., Izzo, V. A., Eidietis, N. W., Lasnier, C. J., Moyer, R. A., Parks, P. B., Foust, C. R., Combs, S., and Meitner, S. J. Radiation asymmetries during disruptions on DIII-D caused by massive gas injectiona). United States: N. p., 2014. Web. doi:10.1063/1.4896721.
Commaux, N., Baylor, L. R., Jernigan, T. C., Hollmann, E. M., Humphreys, D. A., Wesley, J. C., Izzo, V. A., Eidietis, N. W., Lasnier, C. J., Moyer, R. A., Parks, P. B., Foust, C. R., Combs, S., & Meitner, S. J. Radiation asymmetries during disruptions on DIII-D caused by massive gas injectiona). United States. https://doi.org/10.1063/1.4896721
Commaux, N., Baylor, L. R., Jernigan, T. C., Hollmann, E. M., Humphreys, D. A., Wesley, J. C., Izzo, V. A., Eidietis, N. W., Lasnier, C. J., Moyer, R. A., Parks, P. B., Foust, C. R., Combs, S., and Meitner, S. J. 2014. "Radiation asymmetries during disruptions on DIII-D caused by massive gas injectiona)". United States. https://doi.org/10.1063/1.4896721. https://www.osti.gov/servlets/purl/1542704.
@article{osti_1542704,
title = {Radiation asymmetries during disruptions on DIII-D caused by massive gas injectiona)},
author = {Commaux, N. and Baylor, L. R. and Jernigan, T. C. and Hollmann, E. M. and Humphreys, D. A. and Wesley, J. C. and Izzo, V. A. and Eidietis, N. W. and Lasnier, C. J. and Moyer, R. A. and Parks, P. B. and Foust, C. R. and Combs, S. and Meitner, S. J.},
abstractNote = {One of the major challenges that the ITER tokamak will have to face during its operations are disruptions. During the last few years, it has been proven that the global consequences of a disruption can be mitigated by the injection of large quantities of impurities. But one aspect that has been difficult to study was the possibility of local effects inside the torus during such injection that could damage a portion of the device despite the global heat losses and generated currents remaining below design parameter. 3D MHD simulations show that there is a potential for large toroidal asymmetries of the radiated power during impurity injection due to the interaction between the particle injection plume and a large n=1 mode. Another aspect of 3D effects is the potential occurrence of Vertical Displacement Events (VDE), which could induce large poloidal heat load asymmetries. This potential deleterious effect of 3D phenomena has been studied on the DIII-D tokamak thanks to the implementation of a multi-location massive gas injection (MGI) system as well as new diagnostic capabilities. This study showed the existence of a correlation between the location of the n=1 mode and the local heat load on the plasma facing components but shows also that this effect is much smaller than anticipated (peaking factor of ~1.1 vs 3-4 according to the simulations). There seems to be no observable heat load on the first wall of DIII-D at the location of the impurity injection port as well as no significant radiation asymmetries whether one or 2 valves are fired. This study enabled the first attempt of mitigation of a VDE using impurity injection at different poloidal locations. The results showed a more favorable heat deposition when the VDE is mitigated early (right at the onset) by impurity injection. As a result, no significant improvement of the heat load mitigation efficiency has been observed for late particle injection whether the injection is done “in the way” of the VDE (upward VDE mitigated by injection from the upper part of the vessel vs the lower part) or not.},
doi = {10.1063/1.4896721},
url = {https://www.osti.gov/biblio/1542704}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 10,
volume = 21,
place = {United States},
year = {Fri Oct 17 00:00:00 EDT 2014},
month = {Fri Oct 17 00:00:00 EDT 2014}
}

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Free Publicly Available Full Text
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Cited by: 20 works
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Figures / Tables:

Fig. 1 Fig. 1: DIII-D disruption massive gas puff systems (MGI15U and MGI135D) and diagnostics layout.

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Works referenced in this record:

Disruption scenarios, their mitigation and operation window in ITER
journal, March 2007


Disruption mitigation studies in DIII-D
journal, May 1999


Simulation of main chamber wall temperature rise resulting from massive neon gas injection shutdown of ITER
journal, February 2012


Nonlinear magnetohydrodynamics simulation using high-order finite elements
journal, March 2004


Characterization of heat loads from mitigated and unmitigated vertical displacement events in DIII-D
journal, June 2013


Fast‐opening magnetic valve for high‐pressure gas injection and applications to hydrogen pellet fueling systems
journal, September 1986


Impact and mitigation of disruptions with the ITER-like wall in JET
journal, August 2013


Measurements of injected impurity assimilation during massive gas injection experiments in DIII-D
journal, September 2008


Rapid shutdown experiments with one and two gas jets on Alcator C-Mod
journal, August 2013


Experimental study of disruption mitigation using massive injection of noble gases on Tore Supra
journal, July 2010


Gas jet disruption mitigation studies on Alcator C-Mod and DIII-D
journal, August 2007


Experimental vertical stability studies for ITER performance and design guidance
journal, September 2009


Demonstration of rapid shutdown using large shattered deuterium pellet injection in DIII-D
journal, September 2010


Works referencing / citing this record:

Thermal quench mitigation and current quench control by injection of mixed species shattered pellets in DIII-D
journal, June 2016


Measurement of the toroidal radiation asymmetry during massive gas injection triggered disruptions on J-TEXT
journal, October 2018


Injection of multiple shattered pellets for disruption mitigation in DIII-D
journal, September 2019


Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.