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Title: Poloidal radiation asymmetries during disruption mitigation by massive gas injection on the DIII-D tokamak

Authors:
 [1]; ORCiD logo [2];  [3];  [2];  [3]
  1. General Atomics, P.O. Box 85608 San Diego, California 92186-5608, USA
  2. University of California-San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417, USA
  3. Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831, USA
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1392717
Grant/Contract Number:
AC05-00OR22725; FC02-04ER54698; FG02-07ER54917
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 10; Related Information: CHORUS Timestamp: 2018-02-14 13:10:25; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics
Country of Publication:
United States
Language:
English

Citation Formats

Eidietis, N. W., Izzo, V. A., Commaux, N., Hollmann, E. M., and Shiraki, D. Poloidal radiation asymmetries during disruption mitigation by massive gas injection on the DIII-D tokamak. United States: N. p., 2017. Web. doi:10.1063/1.5002701.
Eidietis, N. W., Izzo, V. A., Commaux, N., Hollmann, E. M., & Shiraki, D. Poloidal radiation asymmetries during disruption mitigation by massive gas injection on the DIII-D tokamak. United States. doi:10.1063/1.5002701.
Eidietis, N. W., Izzo, V. A., Commaux, N., Hollmann, E. M., and Shiraki, D. 2017. "Poloidal radiation asymmetries during disruption mitigation by massive gas injection on the DIII-D tokamak". United States. doi:10.1063/1.5002701.
@article{osti_1392717,
title = {Poloidal radiation asymmetries during disruption mitigation by massive gas injection on the DIII-D tokamak},
author = {Eidietis, N. W. and Izzo, V. A. and Commaux, N. and Hollmann, E. M. and Shiraki, D.},
abstractNote = {},
doi = {10.1063/1.5002701},
journal = {Physics of Plasmas},
number = 10,
volume = 24,
place = {United States},
year = 2017,
month =
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on September 19, 2018
Publisher's Accepted Manuscript

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  • Cited by 12
  • 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 ofmore » 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.« less
  • Measurements from the DIII-D tokamak show that toroidal radiation asymmetries during fast shutdown by massive gas injection (MGI) are largely driven by n = 1 magnetohydrodynamic modes during the thermal quench. The phenomenology of these modes, which are driven unstable by pro le changes as the thermal energy is quenched, is described based on detailed magnetic measurements. Here, the toroidal evolution of the dominantly n = 1 perturbation is understood to be a function of three parameters: the location of the MGI port, pre-MGI plasma rotation, and n = 1 error elds. Here, the resulting level of radiation asymmetry inmore » these DIII-D plasmas is modest, with a toroidal peaking factor (TPF) of 1:2 ± 0:1 for the total thermal quench energy and 1:4 ± 0:3 for the peak radiated power, both of which are below the estimated limit for ITER (TPF ≈ 2).« less
  • 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 ofmore » 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. 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