We present a method to control the two-dimensional transverse tilt of the electron bunch originated after the bunch compressor, affecting the X-ray free-electron laser performance. A head–tail tilt in both horizontal and vertical planes leads to a difference between the projected and the slice Twiss parameters, making it difficult to match the electron beam optics to the design one. The primary beam-tilt sources taken into accounts are the CSR generated in the chicane (horizontal tilt) and the misalignment of the high-order cavity used to linearize the compression process (vertical tilt). We show the experimental measurements performed to correct the both-plane beam tilts by using a tweak quadrupole and a skew quadrupole, respectively, placed in the chicane.

我们提出了一种方法来控制电子束的二维横向倾斜，该电子束是在束压缩器之后产生的，影响了X射线自由电子激光的性能。在水平和垂直平面上的头尾倾斜都会导致投影的Twiss参数和切片的Twiss参数之间出现差异，从而使电子束光学器件与设计的匹配变得困难。考虑的主要光束倾斜源是在弯管中产生的CSR（水平倾斜）和用于使压缩过程线性化的高阶腔的未对准（垂直倾斜）。我们展示了通过分别使用调整的四极杆和倾斜的四极杆来校正两平面光束倾斜而进行的实验测量，该四极杆和偏斜四极杆分别放置在弯头中。