Helium transport and exhaust studies in enhanced confinement regimes in DIII-D
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37821 (United States)
- General Atomics, San Diego, California 92186 (United States)
- University of California at Berkeley, Berkeley, California 94720 (United States)
A better understanding of helium transport in the plasma core and edge in enhanced confinement regimes is now emerging from recent experimental studies on DIII-D [{ital Plasma} {ital Physics} {ital and} {ital Controlled} {ital Fusion} {ital Research} (International Atomic Energy Agency, Vienna, 1986), p. 159]. Overall, the results are encouraging. Significant helium exhaust ({tau}{sub He}{sup *}/{tau}{sub {ital E}}{similar_to}11) has been obtained in a diverted, H-mode plasma with edge-localized modes (ELM`s) simultaneous with a central source of helium. There is no evidence of central peaking of the helium density profile even in the presence of this central source. Detailed analysis of the helium profile evolution indicates that the exhaust rate is limited by the exhaust efficiency of the pump ({similar_to}5%) and not by the intrinsic helium transport properties of the plasma. Perturbative helium transport studies using gas puffing have shown that {ital D}{sub He}/{chi}{sub eff} {similar_to}1 in all confinement regimes studied to date (including H mode and VH mode). Furthermore, there is no evidence of preferential accumulation of helium in any of these regimes.
- Research Organization:
- Oak Ridge National Laboratory
- DOE Contract Number:
- AC05-84OR21400; AC03-89ER51114; W-7405-ENG-48; FG03-89ER51121
- OSTI ID:
- 63687
- Journal Information:
- Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 6 Vol. 2; ISSN PHPAEN; ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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