Glinec Y, Faure J, Norlin A, Pukhov A, Malka V
Laboratoire d'Optique Appliquée - ENSTA, UMR 7639, CNRS, Ecole Polytechnique, 91761 Palaiseau, France.
Phys Rev Lett. 2007 May 11;98(19):194801. doi: 10.1103/PhysRevLett.98.194801. Epub 2007 May 9.
We have measured the coherent optical transition radiation emitted by an electron beam from laser-plasma interaction. The measurement of the spectrum of the radiation reveals fine structures of the electron beam in the range 400-1000 nm. These structures are reproduced using an electron distribution from a 3D particle-in-cell simulation and are attributed to microbunching of the electron bunch due to its interaction with the laser field. When the radiator is placed closer to the interaction point, spectral oscillations have also been recorded, signature of the interference of the radiation produced by two electron bunches delayed by 74 fs. The second electron bunch duration is shown to be ultrashort to match the intensity level of the radiation. Whereas transition radiation was used at longer wavelengths in order to estimate the electron bunch length, this study focuses on the ultrashort structures of the electron beam.
我们测量了激光与等离子体相互作用产生的电子束发出的相干光学渡越辐射。对该辐射光谱的测量揭示了电子束在400 - 1000纳米范围内的精细结构。利用三维粒子模拟中的电子分布再现了这些结构，它们归因于电子束与激光场相互作用导致的微聚束。当辐射器放置得更靠近相互作用点时，还记录到了光谱振荡，这是由两个延迟74飞秒的电子束产生的辐射干涉的特征。第二个电子束的持续时间显示为超短，以匹配辐射的强度水平。虽然在较长波长下使用渡越辐射来估计电子束长度，但本研究重点关注电子束的超短结构。
