AN IMPROVEMENT OF MATCHING CIRCUIT OF RF KICKER ELECTRODES

An RF knockout technology [1, 2] is employed as a beam extraction method at the accelerator of The Wakasa Wan Energy Research Center (WERC) An RF noise of which band width is several tens kHz is applied to the transverse kicker electrodes to increase betatron amplitude of the beam. We have improved the beam extraction system in the control of the time-structure of the beam spill by feeding the signal from the spill monitor back to noise amplitude. The feedback control system works as an attenuator, therefore it is necessary to increase the noise amplitude of the kicker electrodes for sufficient effect on the spill shape. In order to enhance the voltage, we improved the matching circuit at the input of the electrodes. By introducing the resonating characteristic at the matching circuit, we obtained 3 times larger amplitude at the electrodes. Shape of the spill became well-controllable by this work, and extraction efficiency is also improved. In the case of a narrowband drive of a capacitive load, the technique presented in this report reduces the drive power drastically. The applications of this technique are, for example, for grid drive of a high power tetrode, that of triode, and drivers of electrostatic devices.