Transverse-to-longitudinal emittance exchange to improve performance of high-gain free-electron lasers.
Transverse-to-longitudinal emittance exchange to improve performance of high-gain free-electron lasers.
复制标题
DOI：
10.1103/physrevstab.9.100702
复制
发表时间：
2006-09
影响因子：
--
通讯作者：
P. Emma;Zhirong Huang;Kwang-je Kim;P. Piot
中科院分区：
文献类型：
--
作者：
P. Emma;Zhirong Huang;Kwang-je Kim;P. Piot
产生小横向发射率的能力可能是高增益 X 射线自由电子激光器 (FEL) 性能的主要限制因素。注意到来自射频光电阴极枪的光束的能量扩散远小于有效 FEL 相互作用所需的能量扩散，我们提出了一种产生约 0.1 {微米}m 或以下的归一化横向发射率的方法，这将导致 X 射线 FEL 项目的波荡器长度显着缩短，电子束能量更低。光束操纵包括通过平面光束技术将最初相等的发射率不等地划分为两个不同的发射率，并用较小的纵向发射率交换较大的横向发射率。我们研究操纵中涉及的各种问题。特别是，我们发现一种新的发射率交换光学器件可以实现该方案所需的精确发射率交换。
The ability to generate small transverse emittance is perhaps the main limiting factor for the performance of high-gain x-rays free-electron lasers (FELs). Noting that beams from an rf photocathode gun can have energy spread much smaller than required for efficient FEL interaction, we present a method to produce normalized transverse emittance at or below about 0.1 {micro}m, which will lead to a significantly shorter length undulator as well as a lower electron beam energy for an x-ray FEL project. The beam manipulation consists of producing an unequal partition of the initially equal emittances into two dissimilar emittances by a flat beam technique and exchanging the larger transverse emittance with a small longitudinal emittance. We study various issues involved in the manipulation. In particular, a new emittance exchange optics we found enables an exact emittance exchange necessary for this scheme.