Acceleration and focusing of multispecies ion beam using a converging laser-driven shock

We demonstrate an ion acceleration scheme capable of simultaneously focusing and accelerating a multispecies ion beam with monoenergetic spectra to a few micron radius. The focal length and ion mean energy can be independently controlled: the former by using a different front-surface shape and the latter by tuning the laser-plasma parameters. We interpret the results using simple models and validate the results using first-principles simulations. The scheme is applicable to different laser transverse profiles and multi-ion species targets, and limiting factors for the ion focusing are delineated. The generated ion beam exhibits high charge, low emittance, and high-energy flux and is of interest for various applications, including inertial confinement fusion, high-flux neutron generation, and biomedical applications.