Realizing Laser-driven Deuteron Acceleration with Low Energy Spread via In-situ D${}_2$O-deposited Target

Generation of quasi-monoenergetic ion pulse by laser-driven acceleration is one of the hot topics in laser plasma physics. In this study, we present a new method for the $\mathit{\text{In-situ}}$ deposition of an ultra-thin D${}_2$O layer on the surface of an aluminum foil target utilizing a spherical D${}_2$O capsule. Employing a 10${}^{19}$ W/cm${}^2$ laser, we achieve the acceleration of 10.8 MeV deuterons with an energy spread of $\mathrm{\Delta }$E/E = 4.6% in the most favorable shot. The energy spread depends on the exposure time of the D${}_2$O capsule in the vacuum chamber. This method has the potential to extend its applicability to other ion species.