Ultrafast electron microscope with high energy electron pulses produced by an intense femtosecond laser

利用飞秒强激光脉冲加速340 keV电子脉冲，对单晶金箔的电子衍射花样进行了单次测量<18>。测量的电子束轮廓忠实地再现的电子轨迹的数值模拟，提供的证据表明，电子脉冲自发地扩展的时间，由于在加速过程中产生的速度扩散，但不失真的不可逆的非线性方式。研究结果表明，激光加速技术在单次激发飞秒电子衍射脉冲压缩技术的发展中具有广阔的应用前景。

We have demonstrated single-shot measurement of electron diffraction patterns for a single-crystal gold foil using 340keV electron pulses accelerated by intense femtosecond laser pulses with an intensity of 2 10^<18>W/cm^2. The measured electron beam profile is faithfully reproduced by the numerical simulation of the electron trajectory, providing evidence that the electron pulse spontaneously expands in time owing to the velocity spread produced in the acceleration process, but is not distorted in an irreversible nonlinear manner. This study shows that the laser acceleration is promising for the development of pulse compression methods for single-shot femtosecond electron diffraction.