Title: Stable monoenergetic ion acceleration by a two color laser tweezer,
Abstract: In the past decades, the phenomenal progress in the development of
ultraintense lasers has opened up many exciting new frontiers in laser matter
physics, including laser plasma ion acceleration. Currently a major challenge
in this frontier is to find simple methods to stably produce monoenergetic ion
beams with sufficient charge for real applications. Here, we propose a novel
scheme using a two color laser tweezer to fulfill this goal. In this scheme,
two circularly polarized lasers with different wavelengths collide right on a
thin nano-foil target containing mixed ion species. The radiation pressure of
this laser pair acts like a tweezer to pinch and fully drag the electrons out,
forming a stable uniform accelerating field for the ions. Scaling laws and
three-dimensional particle-in-cell simulations confirm that high energy
(10-1000 MeV) high charge ($\sim 10^{10}$) proton beams with narrow energy
spread ($\sim4\%-20\%$) can be obtained by commercially available lasers. Such
a scheme may open up a new route for compact high quality ion sources for
various applications.