Experimental and computationalcharacterization of hydrodynamic expansionof a preformed plasma from thin-foil targetfor laser-driven proton acceleration

摘要

We characterize the electron density distributions of preformed plasmafor laser-accelerated proton generation. The preformed plasma of a titanium target3 pm thick is generated by prepulse and amplified spontaneous emission (ASE) ofa high-intensity Ti:sapphire laser and is measured with an interferometer using asecond harmonic probe beam. High-energy protons are obtained by reducing thesize of the preformed plasma by changing the ASE duration before main pulseat the front side (laser incidence side) of the target. Simulation results with two-dimensional radiation hydrodynamic code are close to the experimental resultsfor low-density region x 10' cm-3 at the front side. In the high-density regionnear to the target surface, the interferometry underestimates the density due tothe substantial refraction. The characterization of hydrodynamic expansion withthe interferometer and simulation is a useful tool for investigation of high-energyproton generation.