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Recently JET has been operated with beryllium limiters. This permits a much wider range of operating densities for a given plasma current I(p) than was possible with carbon limiters. The edge value of the cross-field diffusion coefficient D has been deduced from Langmuir probe measurements of the density scrape-off thickness in the SOL. It is thus possible to establish whether D depends on plasma parameters, independent of any dependence on I(p), q or B. It was found that the experimental results for 3 MA, 2.3 T ohmically heated discharges are in fairly close agreement with the Bohm value, i.e., linearly dependent on edge temperature. The edge temperatures and densities are closely coupled, however, and the data can also be reasonably fitted by a term inversely proportional to the square root of the edge density.

Additional information

Authors: STANGEBY P C ET AL., JET Joint Undertaking, Abingdon, Oxon. (GB)
Bibliographic Reference: Report: JET-P(90)11 EN (1990) 12 pp.
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon. OX14 3EA (GB)
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