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Abstract

Stability of the ignition operation with respect to the pure thermal instability is investigated in the case of a temperature dependent non-radiative energy confinement time (tau-E varies as (1/T)**gamma). The thermal stability of the operation with an external power independent of temperature is also studied. The stability criterion is put in the form of a (ntau-E,T) condition. The temperature for divergence leading to the minimum stable ignition is calculated in terms of gamma as well as the corresponding external density power. Special attention is paid to the case of Kaye-Goldston scaling (gamma=1.38). The necessary conditions for dimension and fusion power of an ignited tokamak with Kaye-Goldston scaling are derived taking into account explicit Bremsstrahlung losses and plasma elongation. At the Murakami or beta density limits, realistic dimensions can only be obtained with strong magnetic fields and elongations, but the corresponding high densities yield in turn impracticably large fusion powers. Dimension and density can then be calculated for a fixed power of the reactor (4000 MW(th)). Again reasonable dimensions need high fields and elongations (B-t about 10T, chi about 1.5), but now Murakami and beta limits are never exceeded. The external power necessary for thermal divergence can also be calculated in this case. It is found to be independent of elongation and decreasing with final ignition temperature.

Additional information

Authors: JOHNER J CEA, DEPARTEMENT DE RECHERCHES SUR LA FUSION CONTROLEE, CENTRE D'ETUDES NUCLEAIRES DE CADARACHE, SAINT-PAUL-LEZ-DURANCE (FRANCE), CEA, DEPARTEMENT DE RECHERCHES SUR LA FUSION CONTROLEE, CENTRE D'ETUDES NUCLEAIRES DE CADARACHE, SAINT-PAUL-LEZ-DURANCE (FRANCE)
Bibliographic Reference: WRITE TO CEA, MENTIONING REPORT EUR-CEA-FC 1303 EN, 1986
Availability: Can be ordered online
Record Number: 1989124139100 / Last updated on: 1987-01-01
Category: PUBLICATION
Available languages: en