Hemsing Erik, Halavanau Aliaksei, Zhang Zhen
SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
Phys Rev Lett. 2020 Jul 24;125(4):044801. doi: 10.1103/PhysRevLett.125.044801.
We describe a new method to produce intensity stable, highly coherent, narrow-band x-ray pulses in self-seeded free electron (FEL) lasers. The approach uses an ultrashort electron beam to generate a single spike FEL pulse with a wide coherent bandwidth. The self-seeding monochromator then notches out a narrow spectral region of this pulse to be amplified by a long portion of electron beam to full saturation. In contrast to typical self-seeding where monochromatization of noisy self-amplified spontaneous emission pulses leads to either large intensity fluctuations or multiple frequencies, we show that this method produces a stable, coherent FEL output pulse with statistical properties similar to a fully coherent optical laser.
我们描述了一种在自种子自由电子（FEL）激光器中产生强度稳定、高相干性、窄带X射线脉冲的新方法。该方法使用超短电子束产生具有宽相干带宽的单个尖峰FEL脉冲。然后，自种子单色仪从该脉冲中切出一个窄光谱区域，由长段电子束将其放大至完全饱和。与典型的自种子方法不同，在典型方法中，有噪声的自放大自发辐射脉冲的单色化会导致大的强度波动或多个频率，我们表明该方法产生的稳定、相干FEL输出脉冲具有与完全相干光学激光器相似的统计特性。
