28 GHz 10 kW gyrotron system for electron cyclotron resonance ion source

The 28 GHz gyrotron system (GS) has been purposely designed to meet present-day demand for a microwave source for powering an electron cyclotron resonance ion source capable of producing both high total current and high average ion charge. A gyrotron oscillator of GS operates in both continuous wave and pulse regimes with the output microwave power smoothly regulated in the (0.1-10) kW range. As a whole the functional structure of GS follows the general method of design for feedback controlled microwave sources. The fast feedback loop consists of microwave power detector unit, a purposely developed PC control system, and a high voltage power supply, the regulated voltage from which controls the gyrotron output power. The feedback characteristic time is less than 1 s. The accuracy of a pre-set microwave power maintenance in continuous wave operation of GS is better than 100 W at an output power of 10 kW, and about 50 W at a power of 1 kW. In pulse operation the pulse length can be varied in the range of (1-200) ms with a repetition rate of (200-1) Hz. The leading and trailing edges of the microwave power pulse are 100 mus and less than 10 mus, respectively. The high voltage power supply is furnished with a fast electronic protective system to provide long-term trouble-free operation of gyrotron. The developed PC microwave power control subsystem makes it possible to control the microwave power in both manual and automatic mode. On trials the developed gyrotron system proved itself as versatile, reliable, and user friendly tool applicable for long-term powering of ion sources. (C) 2004 American Institute of Physics.