在LCLS基线处用于APPLE II螺旋辐射器的微束团保持在线系统
Microbunch preserving in-line system for an APPLE II helical radiator at the LCLS baseline
摘要：
在以前的工作中，我们提出了一个计划的偏振控制在LCLS的基线，利用微聚束从平面波荡器。在基线波荡器之后，电子束由FODO聚焦系统传输通过漂移，并通过短螺旋辐射器。微聚束结构可以被保留，并且在螺旋波荡器中以基波发射出强相干辐射。该提议的驱动思想是通过空间滤波来抑制来自基线波荡器的背景线偏振辐射。通过让辐射和电子束穿过螺旋辐射器上游的Be狭缝来实现滤波，其中辐射光斑尺寸比电子束横向尺寸大大约十倍。本文中考虑的几个变化，以改善以前的设计。狭缝现在放置在螺旋形散热器的正后方。其优点是电子束可以被狭缝破坏，并且更窄的狭缝宽度可以用于空间滤波。由于这一根本原因，目前的设置比以前的设置短。螺旋辐射器现在被直接放置在SHAB波荡器的后面。因此，使用SHAB波荡器的现有FODO聚焦系统来传输调制电子束是足够的。本文提出了完整的GENESIS代码计算的新设计，从基线波荡器入口到螺旋形辐射器出口，包括调制电子束传输的SHAB FODO聚焦系统。
英文摘要：
In a previous work we proposed a scheme for polarization control at the LCLS baseline, which exploited the microbunching from the planar undulator. After the baseline undulator, the electron beam is transported through a drift by a FODO focusing system, and through a short helical radiator. The microbunching structure can be preserved, and intense coherent radiation is emitted in the helical undulator at fundamental harmonic. The driving idea of this proposal is that the background linearly-polarized radiation from the baseline undulator is suppressed by spatial filtering. Filtering is achieved by letting radiation and electron beam through Be slits upstream of the helical radiator, where the radiation spot size is about ten times larger than the electron beam transverse size. Several changes considered in the present paper were made to improve the previous design. Slits are now placed immediately behind the helical radiator. The advantage is that the electron beam can be spoiled by the slits, and narrower slits width can be used for spatial filtering. Due to this fundamental reason, the present setup is shorter than the previous one. The helical radiator is now placed immediately behind the SHAB undulator. It is thus sufficient to use the existing FODO focusing system of the SHAB undulator for transporting the modulated electron beam. This paper presents complete GENESIS code calculations for the new design, starting from the baseline undulator entrance up to the helical radiator exit including the modulated electron beam transport by the SHAB FODO focusing system.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
