High power operation at 1.5 MW using the JT-60 gyrotron

Kobayashi, Takayuki; Isayama, Akihiko; Sawahata, Masayuki; Terakado, Masayuki; Shimono, Mitsugu; Igarashi, Koichi; Hinata, Jun; Kajiwara, Ken; Kasugai, Atsushi; Sakamoto, Keishi; Moriyama, Shinichi

High power gyrotron operation at an output power of 1.5 MW was carried out using the JT-60 gyrotron. Pulse length had been limited to 100 ms at an output power of well exceeding 1 MW. An oscillation at 1.5 MW with a pulse length of 1 s was demonstrated, for the first time, in 2007 by the JT-60 gyrotron. We evaluated the heat load on each component of the gyrotron and it was shown that the gyrotron could be operated at 1.5 MW with the pulse length of up to 3 s from the view point of the heat load. In 2009, we tried the operation at the output power of 1.5 MW aiming at the demonstration of the pulse length of 3 s or longer. An operation technique, by which an anode voltage was changed only at the beginning of the pulse, was developed and it resulted in obtaining relatively higher oscillation efficiency. The oscillation at 1.5 MW for 4 s was demonstrated for the first time.