Proton generation from hydrocarbon polymer targets for laser ion source

A laser ion source can provide intense pulsed ion beams from a solid target. On the other hand, generation of a proton beam with a laser ion source requires using compound targets containing hydrogen. In this research, we demonstrated proton generation from three kinds of hydrocarbon polymer targets: polyethylene (C₂H₄)_n, polypropylene (C₃H₆)_n, and polystyrene (C₈H₈)_n. The laser used was a Nd:YAG laser (532 nm/17 ns), and the energy was 0.2 J. The ion current and the fraction of ion species were measured using a Faraday cup and an electrostatic ion analyzer. The results indicated that the peak currents and fraction to total particle number of proton were similar for the different hydrocarbon polymer targets and also showed that increasing the laser intensity effectively increases the number of proton particles because the larger the laser intensity, the larger the total charge.