Helium transport and exhaust studies in enhanced confinement regimes in DIII-D

Conference · Wed Feb 01 04:00:00 EST 1995

OSTI ID:36793

Wade, M R; Hillis, D L; Hogan, J T; Mahdavi, M A; Maingi, R; West, W P; Burrell, K H; Finkenthal, D F; Gohil, P; Groebner, R J ^[1]

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1. and others

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. Overall, the results are encouraging. Significant helium exhaust ({tau}*{sub He}/{tau}{sub E} {approximately} 11) has been obtained in a diverted, ELMing H-mode plasma simultaneous with a central source of helium. Detailed analysis of the helium profile evolution indicates that the exhaust rate is limited by the exhaust efficiency of the pump ({approximately}5%) and not by the intrinsic helium transport properties of the plasma. Perturbative helium transport studies using gas puffing have shown that D{sub He}/X{sub eff}{approximately}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. However, measurements in the core and pumping plenum show a significant dilution of helium as it flows from the plasma core to the pumping plenum. Such dilution could be the limiting factor in the overall removal rate of helium in a reactor system.

• Research Organization: General Atomics, San Diego, CA (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-89ER51114; W-7405-ENG-48; AC05-84OR21400; AC04-76DP00789
• OSTI ID: 36793
• Report Number(s): GA-A--21905; CONF-941101--7; ON: DE95009134
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALPHA PARTICLES
ATOM TRANSPORT
DIVERTORS
DOUBLET-3 DEVICE
H-MODE PLASMA CONFINEMENT
HELIUM ASH
PUMPING