H-mode access in the low density regime on JET

Andrew, Y. and Sartori, R. and Righi, E. and De la Luna, E. and Hacquin, S. and Howell, D.F. and Hawkes, N.C. and Horton, L.D. and Huber, A. and Korotkov, A. and O'Mullane, M.G. and Contributors, JET EFDA (2006) H-mode access in the low density regime on JET. Plasma Physics and Controlled Fusion, 48 (4). pp. 479-488. ISSN 0741-3335 (https://doi.org/10.1088/0741-3335/48/4/001)

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Abstract

1 H-mode access studies under conditions of very low plasma density provide valuable information on the, physics of the edge transport barrier formation and are an important part of the operational scenario development for the next step fusion device, ITER. JET operation with a very low edge electron density, (n) over bar (e) = 0.8-1.4 x 10(19) m(-3), with the MkII gas box septum divertor was found to have a significant effect on the power threshold for the L-H transition, P-th. A sharp `turning point' below which P-th increases with decreasing (n) over bar (e) is found for I-p/B-t values of 2.5 MA/2.7 T, 2.5 MA/2.6T 2.5 MA/2.4T and 2.2 MA/2.4T. The pedestal electron temperature demonstrates a very similar dependence on the edge (n) over tilde (e) as P-th. The role of Z(eff) in the variation of the H-mode power threshold with density is also considered. Shots with the divertor septum present are compared with an identical (n) over bar (e) scan, run with the MkII GB septum replacement plate divertor at 2.5 MA/2.7 T and 2.5 MA/2.6 T. The results from this investigation indicate that removal of the septum may have lowered the (n) over tilde (e) `turning point' for P-th.

  • Item type:Article
    ID code:31300
    Dates:
    Date
    Event
    1 April 2006
    Published
    Subjects:Science > Physics
    Department:Faculty of Science > Physics
    Depositing user: Pure Administrator
    Date deposited:13 Jul 2011 08:56
    Last modified:08 Apr 2024 19:08
    URI:https://strathprints.strath.ac.uk/id/eprint/31300
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