Dynamics of Nanometer-Scale Foil Targets Irradiated with Relativistically Intense Laser Pulses

TL;DR

This study experimentally demonstrates the generation of odd-numbered relativistic harmonics from nanometer-scale foil targets irradiated with intense lasers, confirming long-standing theoretical predictions and enabling in-situ target density measurements relevant for ion acceleration.

Contribution

First experimental observation of odd relativistic harmonics from nanometer foils, verifying the v×B Lorentz force component's role in harmonic generation.

Findings

Confirmed odd relativistic harmonics generation

Enabled in-situ target density measurement

Validated theoretical predictions of harmonic generation mechanisms

Abstract

In this letter we report on an experimental study of high harmonic radiation generated in nanometer-scale foil targets irradiated under normal incidence. The experiments constitute the first unambiguous observation of odd-numbered relativistic harmonics generated by the $\vec{v}\times\vec{B}$ component of the Lorentz force verifying a long predicted property of solid target harmonics. Simultaneously the observed harmonic spectra allow in-situ extraction of the target density in an experimental scenario which is of utmost interest for applications such as ion acceleration by the radiation pressure of an ultraintense laser.