Hot-electron refluxing enhanced relativistic transparency of overdense plasmas

TL;DR

This study reveals that hot-electron refluxing can significantly enhance relativistic transparency in overdense plasmas, enabling laser penetration below traditional thresholds, with implications for laser shaping technologies.

Contribution

The paper introduces the novel phenomenon of hot-electron refluxing enhancing relativistic transparency in overdense plasmas, supported by particle-in-cell simulations.

Findings

Hot-electron refluxing causes overdense plasma to become transparent after a delay proportional to thickness.

Refluxing enhances laser penetration velocity when intensity exceeds SIT threshold.

Simulation results with ion motion confirm refluxing's role in transparency enhancement.

Abstract

A new phenomenon of enhancing the relativistic transparency of overdense plasmas by the influence of hot-electron refluxing has been found via particle-in-cell simulations. When a p-polarized laser pulse, with intensity below the self-induced-transparency (SIT) threshold, obliquely irradiates a thin overdense plasma, the initially opaque plasma would become transparent after a time interval which linearly relies on the thickness of the plasma. This phenomenon can be interpreted by the influence of hot-electron refluxing. As the laser intensity is higher than the SIT threshold, the penetration velocity of the laser in the plasma is enhanced when the refluxing is presented. Simulation data with ion motion considered is also consistent with the assumption that hot-electron refluxing enhances transparency. These results have potential applications in laser shaping.