Escaping Electron from Intense Laser-Solid Interactions as a Function of Laser Spot Size

Abstract

A high powered laser was defocused to observe the effect that this has on the escaping electron population. The data was recorded on Image plate and saved as a .Fit file. Analysis of the diagnostic was conducted using GEANT4 and PIC simulations regarding the self-focusing of the laser on the front surface were also done. Here is the abstract: The interaction of a high-intensity laser with a solid target produces a high-energy distribution of electrons that pass into the target. These electrons reach the rear surface of the target that creates strong electric potentials that restrict the escape of many of the electrons. The measurement of the angle, flux and spectra of the electrons that do escape is able to give insights to the initial interaction. Here, the escaping electrons have been measured from interactions with intensities from 〖10〗^(17-20) W/cm2, where the intensity has been reduced by increasing the size of the focal spot. A curved diagnostic with multiple layers of differentially filtered image plate measures the escaping electrons from the target. An increase in electron flux is observed at an intensity of $ $ which corresponds to a defocus of 100 µm. The peak temperature of the electron distribution is also calculated and found to be relatively constant as a function of laser spot size.