The development of a 1.5 MW, 110 GHz gyrotron for plasma heating

At present, long pulse and CW gyrotrons operating in the 110-170 GHz range typically generate powers up to 1 MW. These are adequate for existing ECH systems used to heat fusion plasmas, but future 5-50 MW systems will require more power per tube in order to be cost effective. As a result there is interest in developing an efficient long pulse or CW industrial multi-megawatt gyrotron. We are in the process of designing and building a 1.5 MW, 110 GHz gyrotron. Our goal is to demonstrate stable, single mode operation with an efficiency >50%. Our plan is to scale the 110 GHz CPI gyrotron that successfully produced 1 MW to higher powers. Two new components will be incorporated into the 1.5 MW tube: a multi-stage depressed collector and a diode electron gun. In order to better understand the unique features of this tube, including the role of trapped and reflected electrons, a short pulse (3 /spl mu/s) prototype will be built and operated at M.I.T., followed by industrial tube development.