Beam loss issue study on the extraction system of a superconducting cyclotron at HUST

• DOI: 10.1016/j.nima.2018.09.126
• Publication Date: 2018-10-01T21:59:32Z
• Authors: Shengwei Hu; Kuanjun Fan; Lige Zhang; Zhiyuan Mei; Xiaofei Li; Zhijie Zeng
• Keywords: 0103 physical sciences; 01 natural sciences; 7. Clean energy

Abstract The study of proton therapy equipment has earned more and more attention in China in recent years. A superconducting cyclotron based proton therapy facility is being developed at Huazhong University of Science and Technology (HUST). Since the proton beam is extracted out of the compact, high energy cyclotron by electrostatic deflectors followed by a series of magnetic channels, the fierce interaction between the proton beam and the deflector septum is the main cause of beam loss, leading to unwanted excess radiation and heat. Excess Radiation effect results in activation or damage to superconducting materials and high risk of quench of superconducting magnets , while thermal effect involves temperature rise and deformation of the septum, both of these phenomena put extraordinary demands on high efficiency extraction of the cyclotron. This paper introduces the design of the electrostatic deflector, including the structure optimization and the material selections. Moreover, in order to minimize the damage to the deflector destruction caused by the proton beam loss, numerical simulations of radiation effect and thermal effect have been conducted by applying Monte Carlo Geant4 code and computational fluid dynamics (CFD) on ANSYS respectively. The energy depositions of the proton beam in diverse septum materials are compared. Meanwhile, the energy and angular distributions of secondary particles are obtained. The maximum temperatures and deformations of the septum in various cases of thickness and material are investigated. The results based on these analyses will give us valuable implications for the development of a superconducting cyclotron.