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Study on Beam Dynamics and Beam Instabilities for a Next Generation Light Source Based on an Energy-Recovery Linac

基于能量回收直线加速器的下一代光源的光束动力学和光束不稳定性研究

基本信息

批准号：
15360507
负责人：
HAJIMA Ryoichi
金额：
$ 4.86万
依托单位：
Japan Atomic Energy Agency (JAEA)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

Energy-recovery linac is a candidate of next-generation X-ray light source, which produces coherent X-rays and femto-second X-rays. Critical issues which determine the performance of ERL light sources have been studied in this project. The issues are (1)beam instabilities due to higher-order modes excited in superconducting cavities, (2)emittance growth due to collective effects through a curved path.For the HOM instability, we developed a particle tracking simulation code to estimate the threshold current of beam break-up. The result of simulation code has been compared with results from other simulation codes. We have also made an experimental study of HOM instability at JAEA ERL, where the injection beam is perturbed by beam deflector at the same frequency as HOM at the main cavity. We have seen enhancement of HOM signals by the deflected beam.For the emittance growth in a curved path, we have proposed linear analysis to calculate the emittance growth due to the collective effects in an electron bunch, which are coherent synchrotron radiation and longitudinal space charge force. The linear analysis can be used to find an optimum beam envelope along a curved path such as injection merger and return loop to minimize the emittance growth.

能量回收直线加速器是下一代X射线光源的候选者，它可以产生相干X射线和飞秒X射线。决定ERL光源性能的关键问题已经在这个项目中进行了研究。针对HOM不稳定性问题，我们开发了粒子跟踪模拟程序来估算束流分裂的阈值电流。并与其它仿真程序的结果进行了比较。我们还在日本原子能机构电子回旋加速器（JAEA ERL）上对HOM不稳定性进行了实验研究，其中注入光束被光束偏转器以与主腔HOM相同的频率扰动。对于弯曲路径下的发射度增长，我们提出了一种线性分析方法来计算由于电子束团中的集体效应（相干同步辐射和纵向空间电荷力）引起的发射度增长。线性分析可以用来找到一个最佳的束流包络沿着一个弯曲的路径，如注入合并和返回回路，以尽量减少发射度的增长。