Institut für Laser- und Plasmaphysik, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf.
Phys Rev E. 2017 Sep;96(3-1):033201. doi: 10.1103/PhysRevE.96.033201. Epub 2017 Sep 18.
We present a new acceleration mechanism for electrons taking place during the interaction of an ultrashort, nonrelativistic laser pulse with a plasma generated at the surface of a solid density target. In our experiments, the plasma is created by a laser pulse with femtosecond duration and an energy of about 1 mJ focused to intensities of above 10^{17}W/cm^{2}. We observe that the electron energies acquired by this mechanism exceed the ponderomotive potential of the laser by an order of magnitude. This result was reproduced and quantitatively confirmed by particle-in-cell simulations, which further revealed that the observed electron acceleration is based on quasistatic electric fields caused by the space charges of ponderomotively preaccelerated electrons. This acceleration process is examined in more detail by a simplified numerical model, which allows a qualitative explanation of the final electron energies.
我们提出了一种新的电子加速机制，该机制发生在超短非相对论激光脉冲与固体密度靶表面产生的等离子体相互作用过程中。在我们的实验中，等离子体是由具有飞秒持续时间和大约 1 mJ 能量的激光脉冲聚焦到超过 10^{17}W/cm^{2}的强度下产生的。我们观察到，通过这种机制获得的电子能量超过激光的 ponderomotive 势一个数量级。粒子模拟进一步证实了这一结果，并定量确认了这一结果，该模拟进一步表明，观察到的电子加速是基于由 ponderomotively 预加速电子的空间电荷引起的准静态电场。通过简化的数值模型更详细地研究了这个加速过程，该模型可以定性解释最终的电子能量。
