Use of Ar pellet ablation rate to estimate initial runaway electron seed population in DIII-D rapid shutdown experiments

Hollmann, E. M.; Commaux, N.; Moyer, R. A.; Parks, P. B.; Austin, M. E.; Bykov, I.; Cooper, C.; Eidietis, N. W.; O’Mullane, M.; Paz-Soldan, C.; Rudakov, D. L.; Shiraki, D.

doi:10.1088/0029-5515/57/1/016008

Title: Use of Ar pellet ablation rate to estimate initial runaway electron seed population in DIII-D rapid shutdown experiments

Journal Article · Mon Oct 03 00:00:00 EDT 2016 · Nuclear Fusion

DOI:https://doi.org/10.1088/0029-5515/57/1/016008· OSTI ID:1372061

Hollmann, E. M. ^[1]; Commaux, N. ^[2]; Moyer, R. A. ^[1]; Parks, P. B. ^[3]; Austin, M. E. ^[4]; Bykov, I. ^[1]; Cooper, C. ^[3]; Eidietis, N. W. ^[3]; O’Mullane, M. ^[5]; Paz-Soldan, C. ^[3]; Rudakov, D. L. ^[1]; Shiraki, D. ^[2]

Univ. of California, San Diego, CA (United States)
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
General Atomics, San Diego, CA (United States)
Univ. of Texas, Austin, TX (United States). Inst. for Fusion Studies
Univ. of Strathclyde, Glasgow (United Kingdom). Dept. of Physics

Small (2–3 mm, 0.9–2 Pa · m³) argon pellets are used in the DIII-D tokamak to cause rapid shutdown (disruption) of discharges. The Ar pellet ablation is typically found to be much larger than expected from the thermal plasma electron temperature alone; the additional ablation is interpreted as being due to non-thermal runaway electrons (REs) formed during the pellet-induced temperature collapse. Simple estimates of the RE seed current using the enhanced ablation rate give values of order 1–10 kA, roughly consistent with estimates based on avalanche theory. Lastly, analytic estimates of the RE seed current based on the Dreicer formula tend to significantly underestimate it, while estimates based on the hot tail model significantly overestimate it.

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Research Organization:: General Atomics, San Diego, CA (United States)

Sponsoring Organization:: USDOE

Contributing Organization:: University of California—San Diego, 9500 Gilman Dr, La Jolla, CA 92093-0417, USA Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA Institute for Fusion Studies, University of Texas at Austin, 2100 San Jacinto Blvd, Austin, TX 78712-1047, USA Department of Physics, University of Strathclyde, Glasgow GW ONG, UK

Grant/Contract Number:: FC02-04ER54698; FG02-07ER54917; AC05-00OR22725; AC52-07NA27344; AC05-06OR23100

OSTI ID:: 1372061

Journal Information:: Nuclear Fusion, Vol. 57, Issue 1; Related Information: E.M. Hollmann, N. Commaux, R.A. Moyer, P.B. Parks, M.E. Austin, I. Bykov, C. Cooper, N.W. Eidietis, M. OMullane, C. Paz-Soldan, D.L. Rudakov, D. Shiraki, "Use of Ar pellet ablation rate to estimate initial runaway electron seed population in DIII-D rapid shutdown experiments", Nuclear Fusion, 57, 1, 2016; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

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Cited by: 11 works

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Pellet-Injector Technology—Brief History and Key Developments in the Last 25 Years Combs, S. K.; Baylor, L. R. Fusion Science and Technology, Vol. 73, Issue 4 https://doi.org/10.1080/15361055.2017.1421367	journal	December 2017
The role of kinetic instabilities in formation of the runaway electron current after argon injection in DIII-D Lvovskiy, A.; Paz-Soldan, C.; Eidietis, N. W. Plasma Physics and Controlled Fusion, Vol. 60, Issue 12 https://doi.org/10.1088/1361-6587/aae95a	journal	November 2018
Physics of runaway electrons in tokamaks Breizman, Boris N.; Aleynikov, Pavel; Hollmann, Eric M. Nuclear Fusion, Vol. 59, Issue 8 https://doi.org/10.1088/1741-4326/ab1822	journal	June 2019

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