Short Intense Laser Pulse Collapse in Near-Critical Plasma

TL;DR

This paper investigates how ultra-short, intense laser pulses interact with near-critical plasma, leading to pulse collapse, localized energy deposition, and relativistic electron acceleration, with implications for ion beam generation.

Contribution

It provides experimental observations and numerical simulations of laser pulse collapse and electron acceleration in near-critical plasma, highlighting magnetic dipole formation and potential ion beam applications.

Findings

Laser pulse collapse causes localized energy deposition.

Relativistic electrons are accelerated during collapse.

Magnetic dipoles are generated, sustaining electron currents.

Abstract

It is observed that the interaction of an intense ultra-short laser pulse with an overdense gas jet results in the pulse collapse and the deposition of a significant part of energy in a small and well localized volume in the rising part of the gas jet, where the electrons are efficiently accelerated and heated. A collisionless plasma expansion over 150 microns at a sub-relativistic velocity (~c/3) has been optically monitored in time and space, and attributed to the quasistatic field ionization of the gas associated to the hot electron current. Numerical simulations in good agreement with the observations suggest the acceleration in the collapse region of relativistic electrons, along with the excitation of a sizeable magnetic dipole that sustains the electron current over several picoseconds. Perspectives of ion beam generation at high repetition rate directly from gas jets are discussed.