Development of High Power Gyrotron with High Performance

Research Project

Project/Area Number	02044159
Research Category	Grant-in-Aid for international Scientific Research
Allocation Type	Single-year Grants
Section	Joint Research
Research Institution	National Institute for Fusion Science
Principal Investigator	OHKUBO Kunizo National Institute for Fusion Science, 教授 (00023739)
Co-Investigator(Kenkyū-buntansha)	ALBERTI S. Centre de Recherches en Physique des Plasmas, Ecole Polytechnique Federale de La, プラズマ物理研究所(スイス), 研究員 TRAN M. Q. Centre de Recherches en Physique des Plasmas, Ecole Polytechnique Federale de La, プラズマ物理研究所(スイス), 主任研究員 SHATZ M. G. Institute of General Physics Academy of Science of the USSR, 一般物理研究所, 研究員 KUBO Shin National Institute for Fusion Science, 助手 (80170025) 佐藤元泰核融合科学研究所, 助教授 (60115855) HOSOKAWA Minolu National Institute for Fusion Science, 助教授 (50115630) 武藤敬核融合科学研究所, 助教授 (90115949) SATO Motoyasu National Institute for Fusion Science MUTOH Takashi National Institute for Fusion Science
Project Period (FY)	1990
Project Status	Completed (Fiscal Year 1990)
Budget Amount *help	¥2,000,000 (Direct Cost: ¥2,000,000) Fiscal Year 1990: ¥2,000,000 (Direct Cost: ¥2,000,000)
Keywords	Gyrotron / Quasi-optics / High power millimeter wave / High performance
Research Abstract	The purpose of this research is to achieve the high-power gyrotron with high performance. High performance is achieved by increment in the mode purity of output millimeter wave, stability of oscillation, and increment in the efficiency such as the energy recovering of the spent electron beam. Investigation of the present status and operation on the quasi-optical gyrotron is important in understanding of the present level. The quasi-optical gyrotron in Lausanne is used for the purpose. The millimeter wave with high power through the Kapton window is generated in the Fabry-Perot resonator with the gold plated mirror. Measurement of power is carried out by using octanol which has good dielectric property with the boiling point of 195 degrees. In the measurement of second harmonic oscillation, it is possible to separate the second harmonics from the fundamental oscillation by using the Macor of solid material which has different absorption coefficient at the second harmonics. Frequency measurement is done by the heterodyne method having the harmonic mixer, where local oscillator is swept to analyze the spectrum. Up to date, the quasi-optical gyrotron has a resonator with edge coupling. Experimental results of output pattern from the annular slotted coupling, cassegrain coupling and a lot of longitudinal slotted coupling shows the distorted pattern unsatisfying from the viewpoint of the coupling to the transmission line. To overcome the disadvantage the combination of the curved mirror and the grating is used. In the low power test, the radiation pattern is good and the figure of merit of gaussian beam is 99%. In addition, from the viewpoint of high performance, investigation of new mode-convertor to gaussian beam with high efficiency is also done. We recognize that the new convertor with the efficiency of 97% is developed by Soviets.