Physical Review X (Nov 2016)
Proton Acceleration Driven by a Nanosecond Laser from a Cryogenic Thin Solid-Hydrogen Ribbon
Abstract
A high-power pulsed laser is focused onto a solid-hydrogen target to accelerate forward a collimated stream of protons in the range 0.1–1 MeV, carrying a very high energy of about 30 J (∼5% laser-ion conversion efficiency) and extremely large charge of about ∼0.1 mC per laser pulse. This result is achieved for the first time through the combination of a sophisticated target system (H_{2} thin ribbon) operating at cryogenic temperature (∼10 K) and a very hot H plasma (∼300 keV “hot electron” temperature) generated by a subnanosecond laser with an intensity of ∼3×10^{16} W/cm^{2}. Both the H plasma and the accelerated proton beam are fully characterized by in situ and ex situ diagnostics. Results obtained using the ELISE (experiments on laser interaction with solid hydrogen) H_{2} target delivery system at PALS (Prague) kJ-class laser facility are presented and discussed along with potential multidisciplinary applications.