Laser Accelerated Ions from a Shock Compressed Gas Foil

TL;DR

This paper demonstrates laser-driven ion acceleration from a shock-compressed gas target, revealing a transition in beam characteristics and the formation of a Z-pinch that enhances ion acceleration.

Contribution

It introduces a novel gas target method for laser ion acceleration and uncovers the role of Z-pinch formation in the process.

Findings

Transition from wide-angle, low-energy to focused, high-energy ion beams

Identification of Z-pinch formation driven by laser wakefield electrons

Enhanced ion acceleration due to combined space charge and Coulombic effects

Abstract

We present results of energetic laser-ion acceleration from a tailored, near solid density gas target. Colliding hydrodynamic shocks compress a pure hydrogen gas jet into a 70 {\mu}m thick target prior to the arrival of the ultra-intense laser pulse. A density scan reveals the transition from a regime characterized by a wide angle, low energy beam to one of a more focused beam with a high energy halo. In the latter case, three dimensional simulations show the formation of a Z-pinch driven by the axial current resulting from laser wakefield accelerated electrons. Ions at the rear of the target are then accelerated by a combination of space charge fields from accelerated electrons and Coulombic repulsion as the pinch dissipates.