Effect of opacity on the density pedestal structure in DIII-D and Alcator C-Mod

S. Mordijck, Richard Joseph Groebner, Tom Osborne, Thomas Neil Carlstrom, Fenton Glass, Philip B. Snyder, Jerry W. Hughes, Aaro E. Järvinen, Antti Salmi, Tuomas Tala, Florian Laggner, George R. McKee, Richard A. Moyer, Terry L. Rhodes, Lei Zeng

Research output: Contribution to conferenceConference AbstractScientific

Abstract

Analysis of experimental data from DIII-D and C-Mod is used to study the role of opacity on the density pedestal structure. Dα measurements at the midplane on DIII-D indicate that we were able to push the ionization front further out by increasing the separatrix and SOL electron densities. We find that in pressure-record breaking EDA H-modes on C-Mod, adding more gas fueling does not result in an increase of the pedestal density, only an increase in the SOL density. In DIII-D, using gas puff modulations, we observe that when the outer strike point detaches, this strongly reduces the amplitude of the electron density response in the SOL and results in a larger amplitude inside the separatrix. Moreover, we observe the creation of an up-down asymmetry in the electron density with increased gas puff/opacity. Close to the X-point, up to ψN ~ 0.98, the electron density is larger than upstream in DIII-D. SOLPS modeling will be performed to get a better evaluation of the poloidal and radial ionization profiles as well as to better understand the origin of the up-down asymmetry of the electron density in DIII-D.
Original languageEnglish
Publication statusPublished - 2018
MoE publication typeNot Eligible
Event60th Annual Meeting of the APS Division of Plasma Physics - Portland, Portland, United States
Duration: 5 Nov 20189 Nov 2018
Conference number: 60
https://www.aps.org/units/dpp/meetings/annual/

Conference

Conference60th Annual Meeting of the APS Division of Plasma Physics
CountryUnited States
CityPortland
Period5/11/189/11/18
Internet address

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opacity
gases
asymmetry
ionization
refueling
upstream
modulation
evaluation
profiles

Cite this

Mordijck, S., Groebner, R. J., Osborne, T., Carlstrom, T. N., Glass, F., Snyder, P. B., ... Zeng, L. (2018). Effect of opacity on the density pedestal structure in DIII-D and Alcator C-Mod. Abstract from 60th Annual Meeting of the APS Division of Plasma Physics, Portland, United States.
Mordijck, S. ; Groebner, Richard Joseph ; Osborne, Tom ; Carlstrom, Thomas Neil ; Glass, Fenton ; Snyder, Philip B. ; Hughes, Jerry W. ; Järvinen, Aaro E. ; Salmi, Antti ; Tala, Tuomas ; Laggner, Florian ; McKee, George R. ; Moyer, Richard A. ; Rhodes, Terry L. ; Zeng, Lei. / Effect of opacity on the density pedestal structure in DIII-D and Alcator C-Mod. Abstract from 60th Annual Meeting of the APS Division of Plasma Physics, Portland, United States.
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title = "Effect of opacity on the density pedestal structure in DIII-D and Alcator C-Mod",
abstract = "Analysis of experimental data from DIII-D and C-Mod is used to study the role of opacity on the density pedestal structure. Dα measurements at the midplane on DIII-D indicate that we were able to push the ionization front further out by increasing the separatrix and SOL electron densities. We find that in pressure-record breaking EDA H-modes on C-Mod, adding more gas fueling does not result in an increase of the pedestal density, only an increase in the SOL density. In DIII-D, using gas puff modulations, we observe that when the outer strike point detaches, this strongly reduces the amplitude of the electron density response in the SOL and results in a larger amplitude inside the separatrix. Moreover, we observe the creation of an up-down asymmetry in the electron density with increased gas puff/opacity. Close to the X-point, up to ψN ~ 0.98, the electron density is larger than upstream in DIII-D. SOLPS modeling will be performed to get a better evaluation of the poloidal and radial ionization profiles as well as to better understand the origin of the up-down asymmetry of the electron density in DIII-D.",
author = "S. Mordijck and Groebner, {Richard Joseph} and Tom Osborne and Carlstrom, {Thomas Neil} and Fenton Glass and Snyder, {Philip B.} and Hughes, {Jerry W.} and J{\"a}rvinen, {Aaro E.} and Antti Salmi and Tuomas Tala and Florian Laggner and McKee, {George R.} and Moyer, {Richard A.} and Rhodes, {Terry L.} and Lei Zeng",
note = "Poster presentation; 60th Annual Meeting of the APS Division of Plasma Physics ; Conference date: 05-11-2018 Through 09-11-2018",
year = "2018",
language = "English",
url = "https://www.aps.org/units/dpp/meetings/annual/",

}

Mordijck, S, Groebner, RJ, Osborne, T, Carlstrom, TN, Glass, F, Snyder, PB, Hughes, JW, Järvinen, AE, Salmi, A, Tala, T, Laggner, F, McKee, GR, Moyer, RA, Rhodes, TL & Zeng, L 2018, 'Effect of opacity on the density pedestal structure in DIII-D and Alcator C-Mod' 60th Annual Meeting of the APS Division of Plasma Physics, Portland, United States, 5/11/18 - 9/11/18, .

Effect of opacity on the density pedestal structure in DIII-D and Alcator C-Mod. / Mordijck, S.; Groebner, Richard Joseph; Osborne, Tom; Carlstrom, Thomas Neil; Glass, Fenton; Snyder, Philip B.; Hughes, Jerry W.; Järvinen, Aaro E.; Salmi, Antti; Tala, Tuomas; Laggner, Florian; McKee, George R.; Moyer, Richard A.; Rhodes, Terry L.; Zeng, Lei.

2018. Abstract from 60th Annual Meeting of the APS Division of Plasma Physics, Portland, United States.

Research output: Contribution to conferenceConference AbstractScientific

TY - CONF

T1 - Effect of opacity on the density pedestal structure in DIII-D and Alcator C-Mod

AU - Mordijck, S.

AU - Groebner, Richard Joseph

AU - Osborne, Tom

AU - Carlstrom, Thomas Neil

AU - Glass, Fenton

AU - Snyder, Philip B.

AU - Hughes, Jerry W.

AU - Järvinen, Aaro E.

AU - Salmi, Antti

AU - Tala, Tuomas

AU - Laggner, Florian

AU - McKee, George R.

AU - Moyer, Richard A.

AU - Rhodes, Terry L.

AU - Zeng, Lei

N1 - Poster presentation

PY - 2018

Y1 - 2018

N2 - Analysis of experimental data from DIII-D and C-Mod is used to study the role of opacity on the density pedestal structure. Dα measurements at the midplane on DIII-D indicate that we were able to push the ionization front further out by increasing the separatrix and SOL electron densities. We find that in pressure-record breaking EDA H-modes on C-Mod, adding more gas fueling does not result in an increase of the pedestal density, only an increase in the SOL density. In DIII-D, using gas puff modulations, we observe that when the outer strike point detaches, this strongly reduces the amplitude of the electron density response in the SOL and results in a larger amplitude inside the separatrix. Moreover, we observe the creation of an up-down asymmetry in the electron density with increased gas puff/opacity. Close to the X-point, up to ψN ~ 0.98, the electron density is larger than upstream in DIII-D. SOLPS modeling will be performed to get a better evaluation of the poloidal and radial ionization profiles as well as to better understand the origin of the up-down asymmetry of the electron density in DIII-D.

AB - Analysis of experimental data from DIII-D and C-Mod is used to study the role of opacity on the density pedestal structure. Dα measurements at the midplane on DIII-D indicate that we were able to push the ionization front further out by increasing the separatrix and SOL electron densities. We find that in pressure-record breaking EDA H-modes on C-Mod, adding more gas fueling does not result in an increase of the pedestal density, only an increase in the SOL density. In DIII-D, using gas puff modulations, we observe that when the outer strike point detaches, this strongly reduces the amplitude of the electron density response in the SOL and results in a larger amplitude inside the separatrix. Moreover, we observe the creation of an up-down asymmetry in the electron density with increased gas puff/opacity. Close to the X-point, up to ψN ~ 0.98, the electron density is larger than upstream in DIII-D. SOLPS modeling will be performed to get a better evaluation of the poloidal and radial ionization profiles as well as to better understand the origin of the up-down asymmetry of the electron density in DIII-D.

M3 - Conference Abstract

ER -

Mordijck S, Groebner RJ, Osborne T, Carlstrom TN, Glass F, Snyder PB et al. Effect of opacity on the density pedestal structure in DIII-D and Alcator C-Mod. 2018. Abstract from 60th Annual Meeting of the APS Division of Plasma Physics, Portland, United States.