High-Order Harmonics from Laser Irradiated Electron Density Singularity Formed at the Bow Wave in the Laser Plasma

The electron density singularity formed at the joining area of relativistic wake wave and bow waves has been proposed as a novel relativistic electron mirror regime to reflect the counter-propagating electromagnetic pulse [1]. Coherent hard electromagnetic radiation is generated by the reflection, compression and frequency upshift from the electron density singularity. In this paper, detailed description of this regime is provided, and new features are shown. The electromagnetic fields reflected by the electron density singularity are investigated via multi-dimensional particle-in-cell simulations.