本文概述了基于粒子加速器的核物理研究主要的前沿方向和重要科学问题,分析了用于核物理研究的粒子加速器大科学装置发展现状和未来发展态势.国家"十二五"重大科技基础设施"强流重离子加速器装置"(High Intensity heavy-ion Accelerator Facility,HIAF)和"加速器驱动的嬗变研究装置"(China Initiative Accelerator Driven System,CiADS)正在广东惠州建设.以HIAF和CiADS为基础,本文提出建设用于核物理及其交叉前沿研究的大型带电粒子加速器集群装置——高亮度电子-离子研究装置(Bright Electron and Ion Research Facility,BEIF).依托BEIF装置拟开展的核物理前沿研究方向包括原子核结构、核天体物理、核子结构、夸克物质相结构,以及基础物理若干重要前沿与核物理的交叉,如高离化态原子物理、重离子驱动的高能量密度物理等.BEIF是由多台超导直线加速器、同步加速器、储存环、反应堆和各类大型实验探测器及实验终端等组成的大科学装置集群.BEIF计划分三期进行建设,建成后的装置将极大地推动我国的核物理和核科学技术研究能力的提升.
The operation of the HIRFL accelerator has shown that the beam transmission efficiency of the sector focusing cyclotron(SFC) injector line is rather poor. Beam simulations have been performed to investigate the possible causes for this low transmission. It is predicted that the property of transversal coupling of the ion beam from electron cyclotron resonance(ECR) ion source can be an important factor to degrade the beam quality by increasing the beam emittance, resulting in a serious particle loss. An improved operation scheme for the SECRAL associated line has been proposed, and the corresponding experiment was carried out. This paper presents the test results.
采用多粒子跟踪程序BEAMPATH对SSC-LINAC重离子RFQ直线加速器进行动力学模拟,分别对RFQ的接受度、高频特性、束流稳定性、空间电荷效应等进行了分析。该RFQ具有很大的纵向接受度,有利于束流在RFQ中的传输;高频特性研究表明,翼间电压设定在理论值以上时,该RFQ都能保持较好的束流特性;束流稳定性分析结果表明,该RFQ具有很大的束流失配容忍度;空间电荷效应研究表明,当束流强度低于0.5 m A时,束流传输不受影响。综合研究结果表明,53.667 MHz重离子RFQ具有较好的动力学特性,满足SSC-LINAC直线加速器的设计要求。
A room temperature heavy ion linac has been proposed as a new injector of the main Cooler Storage Ring(CSRm) at the Heavy Ion Research Facility in Lanzhou(HIRFL), which is expected to improve the performance of HIRFL. The linac injector can supply heavy ions with a maximum mass to charge ratio of 7 and an injection kinetic energy of 7.272 MeV/u for CSRm; the pulsed beam intensity is 3 emA with the duty factor of 3%. Compared with the present cyclotron injector, the Sector Focusing Cyclotron(SFC), the beam current from linac can be improved by 10–100 times. As the pre-accelerator of the linac, the 108.48 MHz 4-rod Radio Frequency Quadrupole(RFQ) accelerates the ion beam from 4 keV/u to 300 keV/u, which achieves the transmission efficiency of 95.3% with a 3.07 m long vane.The phase advance has been taken into account in the analysis of the error tolerance, and parametric resonances have been carefully avoided by adjusting the structure parameters. Kombinierte Null Grad Struktur Interdigital H-mode Drift Tube Linacs(KONUS IH-DTLs), which follow the RFQ, accelerate ions up to the energy of 7.272 MeV/u for CSRm. The resonance frequency is 108.48 MHz for the first two cavities and 216.96 MHz for the last 5 Drift Tube Linacs(DTLs). The maximum accelerating gradient can reach 4.95 MV/m in a DTL section with the length of17.066 m, and the total pulsed RF power is 2.8 MW. A new strategy, for the determination of resonance frequency,RFQ vane voltage and DTL effective accelerating voltage, is described in detail. The beam dynamics design of the linac will be presented in this paper.
