New frontier of laser particle acceleration: driving protons to 93 MeV by radiation pressure

TL;DR

This paper demonstrates the generation of 93 MeV proton beams using radiation pressure acceleration driven by ultra-intense circularly polarized laser pulses, showing a highly efficient method for laser-driven proton acceleration.

Contribution

It reports the first achievement of 93 MeV protons via radiation pressure acceleration with detailed experimental and simulation validation, advancing laser particle acceleration technology.

Findings

Achieved 93 MeV proton energy with circularly polarized laser pulses.

Confirmed radiation pressure acceleration through target optimization and simulations.

Demonstrated quadratic energy scaling and polarization dependence.

Abstract

The radiation pressure acceleration (RPA) of charged particles has been considered a challenging task in laser particle acceleration. Laser-driven proton/ion acceleration has attracted considerable interests due to its underlying physics and potential for applications such as high-energy density physics, ultrafast radiography, and cancer therapy. Among critical issues to overcome the biggest challenge is to produce energetic protons using an efficient acceleration mechanism. The proton acceleration by radiation pressure is considerably more efficient than the conventional target normal sheath acceleration driven by expanding hot electrons. Here we report the generation of 93-MeV proton beams achieved by applying 30-fs circularly polarized laser pulses with an intensity of 6.1 x 1020 W/cm2 to ultrathin targets. The radiation pressure acceleration was confirmed from the obtained optimal target thickness, quadratic energy scaling, polarization dependence, and 3D-PIC simulations. We expect this fast energy scaling to facilitate the realization of laser-driven proton/ion sources delivering stable and short particle beams for practical applications.