Qushan Chen

Design of Gantry Beamline for HUST Proton Therapy Facility

A proton therapy facility with two 360° gantry treatment rooms and one fixed beamline is under development in the Huazhong University of Science and Technology, which is based on the isochronous superconducting cyclotron scheme. This paper presents the beam optics and main magnetic elements including dipoles, quadrupoles, and fast scanning magnets of the gantry beamline. In addition, the energy selection system will be introduced, which enables fast energy modulation of proton beam between 70 and 240 MeV.

Study of beam transverse properties of a thermionic electron gun for application to a compact THz free electron laser

A novel thermionic electron gun adopted for use in a high power THz free electron laser (FEL) is proposed in this paper. By optimization of the structural and radiofrequency (RF) parameters, the physical design of the gun is performed using dynamic calculations. Velocity bunching is used to minimize the bunchs energy spread, and the dynamic calculation results indicate that high quality beams can be provided. The transverse properties of the beams generated by the gun are also analyzed. The novel RF focusing effects of the resonance cavity are investigated precisely and are used to establish emittance compensation, which enables the injector length to be reduced. In addition, the causes of the extrema of the beam radius and the normalized transverse emittance are analyzed and interpreted, respectively, and slice simulations are performed to illustrate how the RF focusing varies along the bunch length and to determine the effects of that variation on the emittance compensation. Finally, by observation of the variations of the beam properties in the drift tube behind the electron gun, prospective assembly scenarios for the complete THz-FEL injector are discussed, and a joint-debugging process for the injector is implemented.