Laser-driven Ion Acceleration In Ultra-thin Targets

Nowadays, with the rapid development of the ultra-short laser pulse technology, the study of ion acceleration driven by the radiation pressure has attracted much attention. However, when the laser pulse irradiates on the ultra-thin target, the targets get deformed easily and the transverse instability comes into appear, which extremely declines the quality of the accelerated ions. Our work is devoted to put forward a scheme to smooth the target deformation and suppress the transverse instability, and finally improve the quality of the accelerated ion beams.Firstly, we investigate the ion acceleration of the ultra-thin target by double parallel Gaussian laser pulses with the 2D3 V code LAPINE. It is shown that the overlapping of two pulses with identical Gaussian profiles can result in a composite light pulse with spatially planar profile, this is conductive to suppress the target deformation and prolong the radiation pressure acceleration process, which eventually improve the maximum energy and the quasi-monoenergetic characteristic of the proton beams. The proton quality can be controlled by adjusting the incidence points of two laser pulses.We also study the interaction of the Gaussian laser pulse with the surface modulated targets. Particle-in-cell simulation shows that strong longitudinal quasi-static magnetic field is generated on the surface of the target, which significantly enhanced the transverse diffusion of electrons. This is beneficial for suppressing the transverse Rayleigh-Taylor-like instability. Finally, the surface of the accelerated proton beams becomes smoother than the case of the planar target, and a final mono-energetic proton beam is obtained by using the surface modulated target.