Enhanced laser-driven ion acceleration by superponderomotive electrons generated from near-critical-density plasma

TL;DR

This paper demonstrates that using a near-critical density plasma layer in laser-driven ion acceleration significantly increases proton energies by generating superponderomotive electrons, supported by experimental and simulation evidence.

Contribution

It introduces a novel double-layer target configuration that enhances ion acceleration via superponderomotive electrons, advancing laser-driven particle acceleration techniques.

Findings

Proton energies increased from 12 to ~30 MeV with the new target.

Superponderomotive electrons were observed with energies beyond the ponderomotive limit.

Simulation results support the experimental interpretation.

Abstract

We report on the experimental studies of laser driven ion acceleration from double-layer target where a near-critical density target with a few-micron thickness is coated in front of a nanometer thin diamond-like carbon foil. A significant enhancement of proton maximum energies from 12 to ~30 MeV is observed when relativistic laser pulse impinge on the double-layer target under linear polarization. We attributed the enhanced acceleration to superponderomotive electrons that were simultaneously measured in the experiments with energies far beyond the free-electron ponderomotive limit. Our interpretation is supported by two-dimensional simulation results.