Author/Authors :
Shimozuma، نويسنده , , T and Kubo، نويسنده , , S and Sato، نويسنده , , M and Idei، نويسنده , , H and Takita، نويسنده , , Y and Ito، نويسنده , , S and Kobayashi، نويسنده , , S and Mizuno، نويسنده , , Y and Yoshimura، نويسنده , , Y and Ohkubo، نويسنده , , K and Funaba، نويسنده , , H and Inagaki، نويسنده , , S and Kobuchi، نويسنده , , T and Masuzaki، نويسنده , , S and Muto، نويسنده , , S and Shoji، نويسنده , , M and Suzuki، نويسنده , , H and Noda، نويسنده , , N and Nakamura، نويسنده , , Y and Kawahata، نويسنده , , K and Ohyabu، نويسنده , , N and Motojima، نويسنده , , O، نويسنده ,
Abstract :
We have developed and constructed an ECH system for the large helical device (LHD). The ECH system consists of 0.5 MW, 84 GHz range and 168 GHz gyrotrons, high voltage power supplies, long distance transmission lines, and in-vessel quasi-optical antennas. It has been improved step by step. At the third campaign of LHD experiments, three 84 GHz range (two 82.6 GHz and one 84 GHz) and three 168 GHz gyrotrons are operated and ECH power can be injected from four antennas vertically and two horizontally. This complicated system is remotely controlled and monitored by fully GUI (Graphical User Interface) control panels realized on PC via TCP (transmission control protocol) communication. Over 10 000 shots of gyrotron power have been injected steadily into the LHD during the experimental campaigns on this system. One line of the system (84 GHz line) is specially prepared for the experiments of steady state plasma production. Using this line, plasma sustainment for 2 min was successfully achieved by only ECH power. Injected ECH power was 50 kW with 95% duty factor. The electron density and temperature of the sustained plasma are measured to be 0.3–0.5×1018 m−3 and ∼650 eV. Ion temperature measured by Doppler broadening of the impurity radiation line was kept constant at ∼300 eV during RF injection.
