We report the generation of ultrashort bright electron pulses directly driven by irradiating a solid target with intense femtosecond laser pulses. The duration of electron pulses after compression by a phase rotator composed of permanent magnets was measured as 89 fs via the ponderomotive scattering of electron and laser pulses, which were almost at the compression limit due to the dispersion of the electron optics. The electron pulse compression system consisting of permanent magnets enabled extremely high timing stability between the laser pulse and electron pulse. The long-term RMS arrival time drift was below 14 fs in 4 h, which was limited by the resolution of the current setup. Because there was no time-varying field to generate jitter, the timing jitter was essentially reduced to zero. To demonstrate the capability of the ultrafast electron pulses, we used them to directly visualize laser pulse propagation in a vacuum and perform 2D mapping of the electric fields generated by low-density plasma in real time.

我们报告了通过用强飞秒激光脉冲照射固体目标直接驱动的超短亮电子脉冲的产生。通过电子和激光脉冲的有质动力散射，测得由永磁体组成的相位旋转器压缩后的电子脉冲持续时间为89 fs，由于电子光学色散，该持续时间几乎处于压缩极限。由永磁体组成的电子脉冲压缩系统使激光脉冲和电子脉冲之间具有极高的定时稳定性。 4 小时内的长期 RMS 到达时间漂移低于 14 fs，这受到当前设置的分辨率的限制。由于没有时变场产生抖动，因此定时抖动基本上减少到零。为了展示超快电子脉冲的能力，我们使用它们直接可视化激光脉冲在真空中的传播，并对低密度等离子体产生的电场进行实时二维映射。