Gamma-Ray Source Based on Laser Acceleration of Electrons from Targets with a Low-Density Plasma Layer

We report a study of electron beams and gamma radiation generation from targets with a preplasma and from targets with an extended plasma of near-critical density on the irradiated side. It is shown that for a laser pulse with an energy of about 1 J, a uniform layer of critical density makes it possible to generate a significantly larger number of high-energy electrons compared to targets with an exponentially decaying preplasma profile produced by the prepulse. The bremsstrahlung gamma radiation spectra of accelerated electron beams in a converter target are constructed, and the possibility of converting the laser pulse energy into gamma radiation energy (with photon energies above 1 MeV) at a level of 5% is demonstrated.