Impact of central ECCD on Steady-state hybrid scenario in DIII-D

C. C. Petty, R. Nazikian, M. A. Van Zeeland, D. C. Pace, B. A. Grierson, Xi Chen, Egemen Kolemen, G. R. McKee, R. Prater, F. Turco

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

"Steady-state" hybrid plasmas in DIII-D with zero surface loop voltage have been maintained for up to two current relaxation times using 3.4 MW of central electron cyclotron current drive (ECCD). In addition to driving ≈0.2 MA of plasma current, central ECCD leads to significant changes in Alfvén eigenmode (AE) activity and thermal transport. For neutral-beam-only heating, strong AE activity is observed that causes a ∼35% degradation in the neutron rate. With central ECCD this AE activity is suppressed, replaced by a bursty energetic particle mode that appears more benign as the neutron rate is closer to the classical value. The electron thermal diffusivity increases by ≈50% for 2.4 MW of ECCD compared to neutral-beam-only cases. Fortunately, the global thermal confinement factor remains the same (H98y2=1.4) as the higher thermal transport for PEC=2.4 MW hybrids is offset by the decreased fast ion transport resulting from AE suppression.

Original languageEnglish (US)
Title of host publicationRadio Frequency Power in Plasmas
Subtitle of host publicationProceedings of the 21St Topical Conference
EditorsRobert I. Pinsker
PublisherAmerican Institute of Physics Inc.
ISBN (Electronic)9780735413368
DOIs
StatePublished - Dec 10 2015
Event21st Topical Conference on Radiofrequency Power in Plasmas - Lake Arrowhead, United States
Duration: Apr 27 2015Apr 29 2015

Publication series

NameAIP Conference Proceedings
Volume1689
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Other

Other21st Topical Conference on Radiofrequency Power in Plasmas
CountryUnited States
CityLake Arrowhead
Period4/27/154/29/15

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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    Petty, C. C., Nazikian, R., Van Zeeland, M. A., Pace, D. C., Grierson, B. A., Chen, X., Kolemen, E., McKee, G. R., Prater, R., & Turco, F. (2015). Impact of central ECCD on Steady-state hybrid scenario in DIII-D. In R. I. Pinsker (Ed.), Radio Frequency Power in Plasmas: Proceedings of the 21St Topical Conference [090002] (AIP Conference Proceedings; Vol. 1689). American Institute of Physics Inc.. https://doi.org/10.1063/1.4936539