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Title: Fast Plasma Shutdowns Obtained With Massive Hydrogenic, Noble and Mixed-Gas Injection in DIII-D

Abstract

Massive gas injection (MGI) experiments with H{sub 2}, D{sub 2}, He, Ne and Ar and 'mixed' (H{sub 2} + Ar and D{sub 2} + Ne) gases injected into 'ITER-similar' 1.3-MA H-mode plasmas are described. Gas species, injected quantity Q, delivery time, t{sub inj}, rate-of-rise and intrinsic and added impurities are found to affect the attributes and 'disruption mitigation' efficacies of the resulting fast plasma shutdowns. With sufficient Q and t{sub inj} < {approx}2 ms, all species provide fast (within {le} {approx}3 ms), more-or-less uniform radiative dissipation of the 0.7-MJ plasma thermal energy and fast but benign current decays with reduced vacuum vessel vertical force impulse. With pure and mixed low-Z gases, free-electron densities up to 2 x 10{sup 21} m{sup -3} are obtained. While these densities are high relative to normal tokamak densities, they are still an order of magnitude smaller than the densities required for unconditional mitigation of the runaway electron avalanche process. Key information relevant to the design of effective MGI systems for larger tokamaks and ITER has been obtained and the collective species and Q-variation data provides a rich basis for validation of emerging 2D + t MHD/transport/radiation models.

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
945694
Report Number(s):
LLNL-CONF-407848
TRN: US0901070
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: Presented at: 22nd IAEA-FEC, Geneva, Switzerland, Oct 13 - Oct 18, 2008
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION; DESIGN; DOUBLET-3 DEVICE; GAS INJECTION; GASES; IMPURITIES; MITIGATION; PLASMA; RUNAWAY ELECTRONS; VALIDATION

Citation Formats

Wesley, J, Hollmann, E, Jernigan, T, Van Zeeland, M, Baylor, L, Boedo, J, Combs, S, Evans, T, Groth, M, Humphreys, D, Hyatt, A, Izzo, V, James, A, Moyer, R, Parks, P, Rudakov, D, Strait, E, Wu, W, and Yu, J. Fast Plasma Shutdowns Obtained With Massive Hydrogenic, Noble and Mixed-Gas Injection in DIII-D. United States: N. p., 2008. Web.
Wesley, J, Hollmann, E, Jernigan, T, Van Zeeland, M, Baylor, L, Boedo, J, Combs, S, Evans, T, Groth, M, Humphreys, D, Hyatt, A, Izzo, V, James, A, Moyer, R, Parks, P, Rudakov, D, Strait, E, Wu, W, & Yu, J. Fast Plasma Shutdowns Obtained With Massive Hydrogenic, Noble and Mixed-Gas Injection in DIII-D. United States.
Wesley, J, Hollmann, E, Jernigan, T, Van Zeeland, M, Baylor, L, Boedo, J, Combs, S, Evans, T, Groth, M, Humphreys, D, Hyatt, A, Izzo, V, James, A, Moyer, R, Parks, P, Rudakov, D, Strait, E, Wu, W, and Yu, J. 2008. "Fast Plasma Shutdowns Obtained With Massive Hydrogenic, Noble and Mixed-Gas Injection in DIII-D". United States. https://www.osti.gov/servlets/purl/945694.
@article{osti_945694,
title = {Fast Plasma Shutdowns Obtained With Massive Hydrogenic, Noble and Mixed-Gas Injection in DIII-D},
author = {Wesley, J and Hollmann, E and Jernigan, T and Van Zeeland, M and Baylor, L and Boedo, J and Combs, S and Evans, T and Groth, M and Humphreys, D and Hyatt, A and Izzo, V and James, A and Moyer, R and Parks, P and Rudakov, D and Strait, E and Wu, W and Yu, J},
abstractNote = {Massive gas injection (MGI) experiments with H{sub 2}, D{sub 2}, He, Ne and Ar and 'mixed' (H{sub 2} + Ar and D{sub 2} + Ne) gases injected into 'ITER-similar' 1.3-MA H-mode plasmas are described. Gas species, injected quantity Q, delivery time, t{sub inj}, rate-of-rise and intrinsic and added impurities are found to affect the attributes and 'disruption mitigation' efficacies of the resulting fast plasma shutdowns. With sufficient Q and t{sub inj} < {approx}2 ms, all species provide fast (within {le} {approx}3 ms), more-or-less uniform radiative dissipation of the 0.7-MJ plasma thermal energy and fast but benign current decays with reduced vacuum vessel vertical force impulse. With pure and mixed low-Z gases, free-electron densities up to 2 x 10{sup 21} m{sup -3} are obtained. While these densities are high relative to normal tokamak densities, they are still an order of magnitude smaller than the densities required for unconditional mitigation of the runaway electron avalanche process. Key information relevant to the design of effective MGI systems for larger tokamaks and ITER has been obtained and the collective species and Q-variation data provides a rich basis for validation of emerging 2D + t MHD/transport/radiation models.},
doi = {},
url = {https://www.osti.gov/biblio/945694}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Oct 14 00:00:00 EDT 2008},
month = {Tue Oct 14 00:00:00 EDT 2008}
}

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