Duris Joseph P, MacArthur James P, Glownia James M, Li Siqi, Vetter Sharon, Miahnahri Alan, Coffee Ryan, Hering Philippe, Fry Alan, Welch Marc E, Lutman Alberto, Decker Franz-Josef, Bohler Dorian, Mock Jeremy A, Xu Chengcheng, Gumerlock Karl, May Justin E, Cedillos Antonio, Kraft Eugene, Carrasco Manuel A, Smith Brian E, Chieffo Logan R, Xu Joseph Z, Cryan James P, Huang Zhirong, Zholents Alexander, Marinelli Agostino
SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
Q-Peak, Inc., Bedford, Massachusetts 01730, USA.
Phys Rev Lett. 2021 Mar 12;126(10):104802. doi: 10.1103/PhysRevLett.126.104802.
We report the demonstration of optical compression of an electron beam and the production of controllable trains of femtosecond, soft x-ray pulses with the Linac Coherent Light Source (LCLS) free-electron laser (FEL). This is achieved by enhanced self-amplified spontaneous emission with a 2 μm laser and a dechirper device. Optical compression was achieved by modulating the energy of an electron beam with the laser and then compressing with a chicane, resulting in high current spikes on the beam which we observe to lase. A dechirper was then used to selectively control the lasing region of the electron beam. Field autocorrelation measurements indicate a train of pulses, and we find that the number of pulses within the train can be controlled (from 1 to 5 pulses) by varying the dechirper position and undulator taper. These results are a step toward attosecond spectroscopy with x-ray FELs as well as future FEL schemes relying on optical compression of an electron beam.
我们报告了利用直线加速器相干光源（LCLS）自由电子激光（FEL）对电子束进行光学压缩以及产生可控的飞秒软X射线脉冲序列的实验演示。这是通过使用2μm激光和一个色散补偿器实现增强的自放大自发辐射来达成的。光学压缩是通过用激光调制电子束的能量，然后用一个弯道磁铁进行压缩来实现的，这导致了电子束上出现高电流尖峰，我们观察到这些尖峰产生了激光。然后使用一个色散补偿器来选择性地控制电子束的激光区域。场自相关测量表明存在一系列脉冲，并且我们发现通过改变色散补偿器的位置和波荡器的渐变，可以控制脉冲序列中的脉冲数量（从1到5个脉冲）。这些结果朝着利用X射线自由电子激光进行阿秒光谱学研究以及未来依赖电子束光学压缩的自由电子激光方案迈出了一步。
