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Abstract

Ignition in the ITER baseline machine (a = 2.15 m, R = 6 m, B(t) = 4.85 T, I(p) = 22 MA), is studied in the frame of a 1/2-D model using the ITER-89P scaling of the energy confinement time. The required value of the enhancement factor with respect to the L-mode, allowing ignition with a total fusion power of 1100 MW, is found to be 1.9 at an optimum operating temperature of 11 keV. A sensitivity analysis shows that the critical value of 2 could be exceeded as a result of relatively small changes in the physical assumptions. It is concluded that the safety margin is not sufficient for this project. Optimisation of a thermonuclear plasma in a tokamak is performed with constraints of a given maximum magnetic field in the superconducting windings, a given distance between the plasma and the maximum magnetic field point, an imposed safety factor at the plasma edge, and a given averaged neutron flux at the plasma surface. It is shown that the minimum enhancement factor with respect to the L-mode, allowing ignition at a given value of the total fusion power, depends only on the torus aspect ratio. Taking the ITER reference values for the above constraints, it is found that the required value of the enhancement factor is practically independent of the aspect ratio but can be sensibly improved by increasing the total fusion power. Analytical expressions of the conditions resulting from the above optimisation are also derived for an arbitrary monomial scaling of the energy confinement time, and give excellent agreement with the numerical results.

Additional information

Authors: JOHNER J, CEA, Département de Recherches sur la Fusion Contrôlée, CEN Cadarache, Saint-Paul-lez-Durance (FR)
Bibliographic Reference: Report: EUR-CEA-FC-1429 EN (1991) 40 pp.
Availability: Available from CEA, Département de Recherches sur la Fusion Contrôlée, Saint-Paul-lez-Durance (FR)
Record Number: 199210156 / Last updated on: 1994-12-02
Category: PUBLICATION
Original language: en
Available languages: en