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

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.

doi:10.1063/1.4896721

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

Journal Article · Fri Oct 17 00:00:00 EDT 2014 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4896721· OSTI ID:1542704

Commaux, N. ^[1]; Baylor, L. R. ^[1]; Jernigan, T. C. ^[1]; Hollmann, E. M. ^[2]; Humphreys, D. A. ^[3]; Wesley, J. C. ^[3]; Izzo, V. A. ^[2]; Eidietis, N. W. ^[3]; Lasnier, C. J. ^[4]; Moyer, R. A. ^[2]; Parks, P. B. ^[3]; Foust, C. R. ^[1]; Combs, S. ^[1]; Meitner, S. J. ^[1]

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Univ. of California San Diego, San Diego, CA (United States)
General Atomics, San Diego, CA (United States)
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

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.

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Research Organization:: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); General Atomics, San Diego, CA (United States)

Sponsoring Organization:: USDOE National Nuclear Security Administration (NNSA); USDOE Office of Nuclear Energy (NE)

Grant/Contract Number:: AC52-07NA27344; AC05-00OR22725; FC02-04ER54698; FG02-07ER54917

OSTI ID:: 1542704

Alternate ID(s):: OSTI ID: 1223598; OSTI ID: 1345230

Report Number(s):: LLNL-JRNL-752015; PHPAEN; 895371

Journal Information:: Physics of Plasmas, Vol. 21, Issue 10; ISSN 1070-664X

Publisher:: American Institute of Physics (AIP)Copyright Statement

Country of Publication:: United States

Language:: English

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Cited by: 20 works

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Measurement of the toroidal radiation asymmetry during massive gas injection triggered disruptions on J-TEXT Tong, R. H.; Chen, Z. Y.; Jiang, Z. H. Review of Scientific Instruments, Vol. 89, Issue 10 https://doi.org/10.1063/1.5035187	journal	October 2018
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The impact of an m / n = 2/1 locked mode on the disruption process during a massive gas injection shutdown on J-TEXT Tong, R. H.; Lin, Z. F.; Liu, L. Z. Nuclear Fusion, Vol. 59, Issue 10 https://doi.org/10.1088/1741-4326/ab32a3	journal	August 2019
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