Abstract
Various improved confinement modes in tokamak are surveyed and their characteristics are reviewed. To search for the potentiality as a fusion core plasma in reactor, an examination to evaluate the core performance has been made. The fusion product near the ignition condition, where Q is large, is used for the evaluation. The dilution of the fuel ion and the profile effect are simultaneously examined together with the obtained τE.
Because of the fuel dilution and of the bulk radiation, the good performance does not always correspond to the mode with long r E. If their time evolution is taken into account the problem becomes more serious. Further extensive research to control the fuel purity is surely needed to ensure the long pulse operation.
