Comparative study of amplified spontaneous emission and short pre-pulse impacts onto fast electron generation at sub-relativistic femtosecond laser-plasma interaction

This paper describes the study of hot electron generation under the action of intense (similar to 10(18) W/cm(2)) femtosecond pulses onto the surface of a solid target, in the presence of a long pre-plasma, which varied with different spatial extents and densities. The corona was formed by pre-pulses with varied intensities and temporal profiles (amplified spontaneous emission (ASE) and short pre-pulses). The most efficient fast electron acceleration, to energies well beyond the ponderomotive potential, was observed if the ASE was able to form to the extent of similar to 100 mu m a slightly undercritical plasma. Energy of accelerated electrons underwent further growth if the laser pulse duration increased from similar to 45 to similar to 350 fs at constant energy fluence. The experimental results were supported by numerical simulations using 3D3V Mandor PIC code. (C) 2014 AIP Publishing LLC.