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Abstract

During ICRF heating in JET, with beryllium gettered walls and RF antenna screens, both the global and local impurity influxes are significantly reduced. In particular oxygen is reduced by an order of magnitude and deuterium is efficiently pumped. Except at the lowest densities a value of 2 for Z(eff) is routinely achieved at P(RF) = 10 MW, and P (rad)/P(tot) is 30% to 50% lower. Assuming the longterm evolution of the beryllium signal at the antenna screen is due to erosion, rather than coverage by carbon, the corresponding influx in monopole configuration is estimated to be 1.16 x E19 atoms/MW/s from an effective area of 0.5m2. At the same coupling resistance the beryllium influx scales with the RF power of the antenna and with the plasma density. With dipoles, the influx is reduced by more than a factor 3. The contribution of antenna influxes to Z(eff) is small.

Additional information

Authors: BURES M, JET Joint Undertaking, Abingdon, Oxon. (GB);JACQUINOT J, JET Joint Undertaking, Abingdon, Oxon. (GB);STAMP M, JET Joint Undertaking, Abingdon, Oxon. (GB);LAWSON K, JET Joint Undertaking, Abingdon, Oxon. (GB);THOMAS P, JET Joint Undertaking, Abingdon, Oxon. (GB)
Bibliographic Reference: Report: JET-P(89)72 EN (1989) 19 pp.
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon. OX14 3EA (GB)
Record Number: 199011435 / Last updated on: 1994-12-02
Category: PUBLICATION
Original language: en
Available languages: en