Enhanced proton acceleration and collimation via vortex laser irradiated micro-tube foil target

Abstract

Laser-driven particle acceleration has attracted significant attention due to its potential for compact and cost-effective particle accelerator. Currently, the generation of highly collimated high-energy proton beams, essential for fundamental science and industry, remains a notable challenge using this technique. Here we present an effective scheme for generating such a high-quality proton beam via a circularly polarized Laguerre–Gaussian (LG) laser pulse irradiating a micro-tube foil target. Three-dimensional particle-in-cell simulations show that numerous overdense electron bunches are pulled out from the micro-tube and accelerated forward by the laser fields, inducing a strong converging sheath field at the rear side of the target. As a result, highly collimated protons are accelerated forward by this sheath field, exhibiting a high-flux of 3 × 107 protons/MeV at a cutoff energy of 125 MeV, achieved at a LG laser intensity of 1.71 × 1021 W cm−2. This high-quality proton beam is desirable for medical and biophysical applications, such as FLASH radiotherapy.