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Measurements of the electron heat diffusivity (x) of the JET plasma in a wide variety of discharge conditions are reported. Heat pulse propagation analysis is used to deduce x, using the sawtooth collapse as the perturbation of the temperature profile. The measurements of the electron temperature are performed with a 12-channel ECE polychromator. In limiter discharges, scans of plasma current, density, input power and Z(eff) were studied. It is shown that x is independent of density and input power, while a clear dependence of Z(eff) and of the electron temperature is demonstrated. The scaling provides a good fit to the JET data. The dependence of the normalised radius where x is measured, coupled to q(a) only parametrises the combined effect of plasma current and profile shapes of temperature, density, safety factor etc. Various transport models are discussed in the light of the scaling. Secondly, it is demonstrated that in X-point discharges x in the confinement region does not change when going from L-mode to H-mode.

Additional information

Authors: LOPES CARDOZO N J, JET Joint Undertaking, Abingdon, Oxon. (GB);DE HAAS J C M, JET Joint Undertaking, Abingdon, Oxon. (GB)
Bibliographic Reference: Report: JET-P(89)78 EN (1989) 20 pp.
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon. OX14 3EA (GB)
Record Number: 199011144 / Last updated on: 1994-12-01
Original language: en
Available languages: en