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Abstract

The particle and energy transport properties of the high fusion performance JET pulses that were obtained before and during the first tritium experiments are discussed. The particle diffusion coefficient of tritium is determined by monitoring the decay of a small quantity of injected tritium in a deuterium background plasma. A good simulation of the measured 14 MeV emissivity profile is obtained throughout the decay phase, if the mixing of the two species is described by a model in which the tritium diffusion coefficient is similar to that of the deuterium. A local transport analysis is completed to try to establish the reason for the improvement observed in the confinement. Several possibilities are investigated, including stabilisation of the eta(i) mode by the peaked density profile and access to the second ballooning mode stable region. Finally, for the discharge with a high concentration of tritium, it is suggested that alpha-particle driven instabilities could affect the energy confinement. A comparison is made with the stability threshold of toroidicity induced Alfvén eigenmodes (TAE) and the alpha-particle statistics are presented.

Additional information

Authors: BALET B ET AL., JET Joint Undertaking, Abingdon, Oxon. (GB);BORBA D, Instituto Superior Technico, Centro de Fusao Nuclear, Lisboa (PT);GREENFIELD C M, General Atomics, San Diego (US);NAVE M F, Laboratorio Nacional de Engenharia e Technologia, Lisboa (PT)
Bibliographic Reference: Report: JET-P(93)18 EN (1993) 49 pp.
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon. OX14 3EA (GB)
Record Number: 199310910 / Last updated on: 1994-11-29
Category: PUBLICATION
Original language: en
Available languages: en