Ion Acceleration via "Nonlinear Vacuum Heating" by the Laser Pulse Obliquely Incident on a Thin Foil Target

TL;DR

This paper investigates how laser polarization affects ion acceleration energy when a laser pulse interacts with a thin foil, revealing the roles of anomalous electron heating mechanisms like nonlinear resonance and stochastic heating.

Contribution

It introduces a theoretical model explaining electron anomalous heating and its impact on ion acceleration, highlighting the influence of laser parameters and polarization.

Findings

Ion energy peaks for p-polarization and decreases with s-polarization.

Electron heating exceeds quiver motion energy, driven by nonlinear and stochastic regimes.

Ion energy scales with laser intensity, pulse duration, and incident angle.

Abstract

Dependence of the energy of ions accelerated during interaction of the laser pulse obliquelly incident on the thin foil target on the laser polarization is studied experimentally and theoretically. We found that the ion energy being maximal for the p-polarization gradually decreases when the pulse becomes s-polarized. The experimentally found dependences of the ion energy are explained by invoking the anomalous electron heating which results in high electrostatic potential formation at the target surface. Anomalous heating of electrons beyond the energy of quiver motion in the laser field is described within the framework of theoretical model of driven oscillator with a step-like nonlinearity. We have demonstrated that the electron anomalous heating can be realized in two regimes: nonlinear resonance and stochastic heating, depending on the extent of stochasticity. We have found the accelerated ion energy scaling determined by the laser intensity, pulse duration, polarization angle and incident angle.