An investigation of the power balance associated with recycling in JET ohmic limiter dischargesFunded under: FP2-FUSION 10C
The power flow to the beryllium toroidal limiters in JET, determined by Langmuir probes, is lower than the input power to the plasma edge. This can partly be explained by considering the excess ion temperature over electron temperature and partly by systematic errors. However, at high densities it is necessary to account further for the power losses associated with recycling. When a beryllium atom enters the plasma from the limiter, it is ionised and, during the early transient stages towards full ionisation, significant radiation occurs. The beryllium ions could undergo charge exchange with the recycling hydrogen atoms which surround them, so that the population of the lower charge states would be enhanced and the radiation losses would therefore increase. To study these losses a model of the beryllium and hydrogen behaviour is required, which takes the geometry of the recycling region into account and explains why the bolometer in JET ignores this radiation. This paper describes an analytical approach which accounts for variations in plasma profile and also geometrical effects.
Bibliographic Reference: Report: JET-P(91)22 EN (1991) 4 pp.
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon. OX14 3EA (GB)
Record Number: 199111582 / Last updated on: 1994-12-02
Original language: en
Available languages: en