Preliminary assessment of Ignitor performances

Thermal equilibrium O-D calculations are shown to give useful information in the case of non-stationary discharges if a proper generalization of the plasma amplification factor Q* is chosen. With this definition, Q*=∞ corresponds to a plasma state where Pα Ploss. This approach is used for a preliminary assessment of Ignitor performances. For parabolic density and temperature profiles, it is shown that Q*=∞ can be obtained in this machine only for an enhancement factor HL with respect to ITER-97P(th) scaling law of the energy confinement time of the order of 1.9. Using ITER-FEAT assumptions for the density and temperature profiles, it is shown that Q*=∞ can be obtained in H-mode with IPB98(y,2) scaling of the energy confinement time. Analysis of the reference operating point of Ignitor proposed by Coppi et al. shows that their alpha power and energy content can be reproduced only with peaked density and temperature profiles. With such profiles, Q*=∞ still requires an enhancement factor HL of 1.44. (author)