Sustained high beta plasmas with negative central shear in DIII-D

A. M. Garofalo, E. J. Doyle, C. M. Greenfield, A. W. Hyatt, G. L. Jackson, R. J. Jayakumar, C. E. Kessel, J. Y. Kim, R. J. La Haye, M. Murakami, M. Okabayashi, H. Reimerdes, J. T. Scoville, H. E.St John, E. J. Strait

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Simultaneous ramping of the plasma current and toroidal field, and application of early neutral beam heating in DIII-D have produced current-hole type discharges sustained for ≈2s at high values of normalized pressure (βN≈ 4) and safety factor (qmin ≈ 2). The combination of internal transport barrier and negative central magnetic shear results in high energy confinement (H89 > 2.5) and good bootstrap current alignment (fBS ≈ 60%). Previously, stability limits in plasmas with core transport barriers have been observed at moderate values of βN(<3) because of characteristically high pressure-peaking. A noninductive current fraction of ≈90% has been observed at plasma β ≈ 5% in these DIII-D experiments. Stability modeling shows the possibility for operation up to β ≈ 6%, suggesting a possible path to high fusion performance, steady-state tokamak scenarios with a large fraction of bootstrap current.

Original languageEnglish
Title of host publication32nd EPS Conference on Plasma Physics 2005, EPS 2005, Held with the 8th International Workshop on Fast Ignition of Fusion Targets - Europhysics Conference Abstracts
Pages145-148
Number of pages4
StatePublished - 2005
Externally publishedYes
Event32nd European Physical Society Conference on Plasma Physics and Controlled Fusion combined with the 8th International Workshop on Fast Ignition of Fusion Targets - Tarragona, Spain
Duration: Jun 27 2005Jul 1 2005

Publication series

Name32nd EPS Conference on Plasma Physics 2005, EPS 2005, Held with the 8th International Workshop on Fast Ignition of Fusion Targets - Europhysics Conference Abstracts
Volume1

Conference

Conference32nd European Physical Society Conference on Plasma Physics and Controlled Fusion combined with the 8th International Workshop on Fast Ignition of Fusion Targets
Country/TerritorySpain
CityTarragona
Period06/27/0507/1/05

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