11MeV氘离子直线加速器小型化关键技术研究

The deuteron linac for the new neutron imaging detector system need to be designed compact because of the spare space of the existing nuclear device. The deuteron linac generally consists of the deuteron ion source (IS), the low energy beam transport, the radio-frequency-quatrupole (RFQ) linac and the compact drift tube linac. This project will investigate the beam dynamics of the RFQ and DTL, which are the key components of the system, using the simulating software like RFQGEN and PARMILA. For the dynamic study of IH-DTL, we will develop the customized program based on MATLAB programming language. We will design the RF structures using the microwave design software like SUPERFISH, CST and HFSS according the dynamic design results. Finally we can achieve the physics design of the whole deuteron linac. In this research procedure, we want to solve the key problems like field strength enhancing, directly matching and energy dividing of the RFQ and IH-DTL. As the preponderance, we can share the design and engineering experience of the CPHS project in Tsinghua University. Some necessary verification experiments which make the investigating results more reliable can also be achieve on the RFQ and so on in Tsinghua University. As results, the research achievements could guide the following engineering studies for the compact neutron imaging detector system in the future.

用于中子成像的氘氘中子反应系统对氘离子直线加速器提出了小型化的需求。本项目拟通过对 RFQ、IH-DTL 等核心组件的动力学理论研究，借助 RFQGEN、PARMILA 等动力学仿真软件，并自主开发用于 IH-DTL 动力学研究的程序，开展对小型化氘离子直线加速器紧凑型 RFQ 动力学、高梯度 IH-DTL 动力学等关键技术的研究，根据动力学设计结果，通过 SUPERFISH、CST、HFSS 等射频仿真程序，进行射频结构设计，从而完成对 11 MeV 小型氘离子直线加速器物理设计。该项目拟重点解决小型化氘离子直线加速器中提高 RFQ 和 IH-DTL 场强、RFQ 与 IH-DTL 直接匹配以及 RFQ 到 IH-DTL 的能量分界等问题。研究过程中，可充分利用清华大学在 RFQ 、DTL 的相关设计经验和工程经验，并在清华大学已经建成的离子源、LEBT、RFQ 等设备上进行验证实。

在项目执行期间完成了一台11 MeV小型氘离子直线加速器的物理设计方案。直线加速器系统主要包含一台电子回旋共振（ECR）氘离子源（IS）、静电低能传输段（LEBT）、四翼型射频四极（RFQ）加速器、交叉指形H模（IH）漂移管直线加速器（DTL）及固态功率源系统。设计方案主要包括RFQ和IH DTL的束流动力学设计和高频结构设计，ECR离子源、静电LEBT和功率源的技术路线。为了实现加速器的小型化，针对加速器的射频频率、IH DTL加速单元的射频结构、RFQ与IH DTL能量分段点进行了优化。RFQ和DTL的总长最终设计结果为4.53米，其中RFQ长度为1.93米、DTL长度为2.60米，RFQ与DTL之间采用直接匹配设计。为了验证IH DTL物理设计方法的合理性，清华大学加工了一台325MHz质子IH DTL加速器并成功完成了束流测试。