China
Africa
Explore chapters and articles related to this topic
RF Systems for Heating and Current Drive in Fusion Experiments
Published in R A Cairns, A D R Phelps, P Osborne, Generation and Application of High Power Microwaves, 2020
The condition for multipactor effect is that the electron transit time must equal the RF half period, or its harmonics. This condition can be fulfilled not only when electrons bounce back and forth between two surfaces, but also with a single surface when a magnetic field is present, the resonance condition being such that the electron gyro frequency equals the RF frequency or its sub-harmonics.
Measurement of voltage and power of RF cavity with capacitor probe in SC200 cyclotron
Published in Journal of Nuclear Science and Technology, 2021
Zhen Peng, Gen Chen, Yan-Ping Zhao, Yun-Tao Song, Xin Zhang, G. Shirkov, G. Karamysheva, O. Karamyshev, W. Chuansong
The SC200 cavity has been designed to accelerate protons up to 200 MeV for proton therapy [1,2]. To assess the characteristics and performance of the cavity in the designed model, in a cool-measured and high-power platform, the main parameters used are driver power and buildup voltage of the cavity. The driver power () is the power consumed by the RF cavity to establish the cavity voltage () under ideal conditions. In the cool measurement, the driver power is equal to the net power () measured with the difference between the forward power () and the reflection power (), and the buildup voltage () in the cavity can be expressed as, where is the simulated shunt impedance of the spot of interest in the cavity [3,4]. However, at high power, not all net power () from the power source is used as the driver power (),, where the residual power () may contribute to the increase in the resistance of the RF cavity material and the dielectric loss caused by the gas desorption of the cyclotron components or multipactor effect of the cavity [5,6]. Consequently, monitoring the driver power, residual power, and buildup voltage to obtain a fundamental understanding of the cavity performance and multipactor is essential, as it affects the potential development and modification of the RF cavity.