Enhancing laser-driven proton acceleration using a lithium target

Laser-plasma acceleration of ions has been of interest for the past few decades. An effective way to enhance laser-driven proton acceleration is to improve laser absorption in plasmas. In this study, we show that lithium (Li) is the most promising candidate for accelerating protons with better absorption among target light weight materials used for ion acceleration. For this, two-dimensional particle-in-cell (PIC) simulations were performed to investigate the acceleration of ions and protons with a high-power laser (with an amplitude a0=10 and a pulse duration of 30 fs) to determine the optimal lithium target thickness for maximum energies. The maximum energy of Li ions is achievable with a target thickness of 40 nm, while the maximum proton energy can be achieved for a 30nm thickness of the target. Moreover, a series of PIC simulations were also performed with targets of different atomic numbers and thicknesses to understand lithium's performance for the acceleration of protons. Compared to other targets, such as Al (Aluminum), C (Carbon), and Be (Beryllium), the Li target has a significant enhancement in proton energy, which can be used as an alternative target to enhance proton and ion energies in future experiments.