Study Of APF IH-DTL Proton Accelerating Structure

Malignant tumors have become the main threat to the human being's health.It is an urgent task to conquer cancers and increase the survival rate and improve life quality of cancers patients during treatment or after treatment.Because of the unique Bragg Peak of energetic proton beams,which leads to higher quality of life for patients and clinical effects,proton accelerators are getting more and more attention now.Injector is one of the core components of proton medical accelerator.Then developing an injector of high-performance cost ratio plays an important role for the popularization of proton therapy.A typical injector for the proton medical accelerator mainly consists of four components,including an Ion Source(IS),a Low Energy Beam Transport(LEBT)section,a Radio Frequency Quadrupole(RFQ)and a conventional Alvarez-type Drift Tube Linac(DTL)one after another.My work of this dissertation focuses on the development of a DTL featured compact,easy-to-maintenance and cost-efficient to replace the conventional DTL in massive production phase.The Interdigital-H-mode DTL(IH-DTL)structure with Alternating Phase Focused(APF)method is adopted in our work.Based on the two features,we designed an APF IH-DTL cavity,this structure significantly reduces the size longitudinally and radially,meanwhile there is no demand for the electro-quadrupoles and relevant power supplies and water-cooling systems,and further reduces the demand for the maintenance.These advantages make the proton therapy more competitive.As the first self-developed and implemented APF IH-DTL,and also the first APF IH-DTL working at 325 MHz,not only developing a cavity meets the requirements from beam dynamics,but also we developed an efficient procedure to design a cavity like this.Meanwhile we studied the main RF characters and relations to the components,such as cavity radii,tuner depth,ridge width and so on.To verify the design and processing technology,we developed the first cold test cavity of eight cells,all the measured results such as frequency,gap-voltages distribution,electric field distribution,the ability of tuners,S11 and Q value meet the designed value,which indicates a good cold test cavity.The exploration of above processing,assembling,measuring and tuning lay a solid foundation for the future highpower working cavity.