Simulation of DC-Superconducting RF Gun

(MO-3-17)

Kui Zhao, Jiankui Hao, Yanle Hu, Xi Yang, Baocheng Zhang, Shengwen Quan, Senlin Huang, Chen Jiaer  

Peking University

The most characteristic advantage of superconducting photocathode RF electron gun is that it can work with CW mode. It is suitable for the injector of high average power Free Electron Laser (FEL). To develop this kind of RF gun, the photocathode is set inside of superconducting cavity and the electrons are controlled by the transverse properties. This brings difficulties to the injector. To solver this problem, we designed the DC-Superconducting RF gun. It consists of three components, DC extraction gap, 1+1/2 superconducting cavity and coaxial microwave input system. The DC gap, which is a Pierce configuration, is connected with the 1+1/2 superconducting cavity. The photocathode is on the negative electrode of the DC gap. The anode is the bottom of the 1/2 cavity. The photocathode is outside of the superconducting cavity to avoid the influence on the wall of the cavity. DC gap and superconducting cavity acceleration can provide CW electron beam. Coaxial microwave input system is beneficial to the near field in the cavity.

We made simulations on the beam dynamic of the electron beams extracted by DC gap and accelerated by superconducting cavity. In the simulation, the charge of electron beam bunch is about 60 pC, the repetition frequency is around MHz. It is the expected result.

We have finished the optimization and experiments of the DC gap, the design and experiments of the coaxial coupler. A optimized 1/2 superconducting cavity is in the process of study and manufacture.