Generating high-current quasi-monoenergetic MeV ions via laser-driven TNSA-based dechirp

The generation of high-current MeV carbon ions from plasma by using two sequential laser pulses has been investigated with the help of three-dimensional particle-in-cell simulations. When the first laser pulse drives the expansion of the target, target-normal sheath acceleration happens, and the accelerated ions are momentum-chirped. The second laser pulse drives an additional target-normal sheath field, which has a monotonically decreasing front. The field moves together with a group of the chirped ions and dechirps them, thereby making them quasi-monoenergetic. Simulations show that, by using two laser pulses with the total laser energy of 8.5 J, a carbon ion beam with energy spectrum peaked at 1.1 MeV/u, an ion number up to 4×1011/MeV, and a divergence angle about 5° can be produced. These ions can be utilized for applications requiring high current low-energy ions with narrow energy width, especially as an injection source in traditional RF accelerators for carbon ion FLASH radiotherapy.