Observation of Preformed Plasma Generated from a Thin-Foil Target for Laser-Driven Proton Acceleration

Abstract

We have measured the proton yield from thin-foil targets irradiated with a high-intensity Ti:sapphire laser. The longitudinal extent of the preformed plasma protruding from the front surface of the target is reduced by decreasing the duration of the amplified spontaneous emission (ASE) before the main pulse. The maximum proton energy in the target normal direction increases when the size of the preformed plasma is controlled.