摘要:
为了提高兰州重离子加速器冷却储存环（HIRFL-CSR）的运行效率、改善加速器输出束流品质，并实现几个加速装置分时供束，提高整个重离子加速装置的利用率，特为（HIRFL-CSR）增建一台新的注入器——CSRLINAC。在108.48 MHz的RFQ之后的CSR-LINAC主加速段，主要由一台108.48 MHz和两台216.96 MHz的IH型漂移管直线加速器组成，用于加速荷质比为1/8.5~1/3之间的重离子，其最大的束流流强为3 mA，并将粒子从0.3 MeV/u加速到3.71 MeV/u。运用KONUS动力学原理，在满足设计指标的情况下，首先利用TraceWin程序进行中能束线MEBT设计，后针对高频腔体设计和束流匹配的基本参数的系列讨论，特别是对CSR-LINAC的中能束流匹配线、参数选择和IH型KONUS结构的漂移管直线加速器进行设计模拟优化。最终得出，在保证腔体设计指标和95.3%的传输效率的情况下，该紧凑型直线加速结构经过三个腔体的加速后，束流的纵向归一化均方根发射度增长仅有25%；同时发现，当流强达到3 mA时，存在空间电荷效应，导致其纵向相宽增长约25%，最大横向包络也存在16.5%的涨落。
In order to improve the operation efficiency of the Cooling Storage Ring of Heavy Ion Research Facility in Lanzhou (HIRFL-CSR), a heavy ion linac (linear accelerator) was proposed and designed as a new injector for HIRFL-CSR. Following the 108.48 MHz Radio-Frequency Quadrupole (RFQ), three tanks in total with Interdigital H-mode drift tube linac (IH-DTL) structure are installed to boost the beam energy from 0.3 to 3.71 MeV/u, and the beam current of ions with charge-to-mass ratio from 1/8.5 to 1/3 can reach to 3 mA. The first tank operatesat the same frequency as the RFQ, and the rest two operate at 216.96 MHz. The “Combined Zero-Degree Synchronous Particle Structure” (KONUS) beam dynamics was used in the beam dynamics design. The overview of the physics design on the main accelerating components, including RF design and beam dynamics design are introduced in this paper. The optimized structure design, fabrication status and simulation results are presented in this contribution. It shows that under the condition of assurance of 95.3% transmission efficiency, the normalized rms emittance is about 25%. When the beam current is up to 3 mA, owing to the space charge effect, the increase of longitudinal phase spread and transverse envelope are about 25% and 16.3%, respectively.
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