Annual report of the Naka Fusion Research Establishment for the period of April 1 1988 to March 31 1989

The experiment on JT-60 was resumed in May 1988 after the modification of the divertor configuration into a lower single-null type. An improved confinement associated with significant remote radiative cooling at the divertor region was obtained. In the confinement experiment on JFT-2M, an improved L mode was also obtained, in which density profile is peaked without edge pedestal in contrast to the H-mode confinement. A system test of a turbo molecular pump with a gas turbine-driven ceramic rotor successfully demonstrated a pumping speed. A 400 KW electron beam irradiation system was constructed for development of high heat flux components. The Large Coil Task, a ten-year long international collaboration under the auspices of the IEA, was successfully completed in January 1989. The International Thermonuclear Experimental Reactor (ITER) Conceptual Design Activity was initiated under the auspices of the IAEA. (J.P.N.)