Prof Peter Norreys FInstP;

Abstract:

The ultraintense laser plasma interaction experiments have produced observations of new phenomenon such as: the acceleration of electrons to high energies; production of intense proton beams; and the generation of magnetic fields. Observations of proton emission indicate significant structure in the energy spectrum and angular emission profile which varies with energy. The two different components of ion emission observed are a high energy component and a low energy component.

Abstract:

The angular distribution of bremsstrahlung gamma rays produced by fast electrons accelerated in relativistic laser-solid interaction has been studied by photoneutron activation in copper. We show that the gamma-ray beam moves from the target normal to the direction of the k(laser) vector as the scale length is increased. Similar behavior is found also in 2D particle-in-cell simulations.

Abstract:

Protons with energies up to 18 MeV have been measured from high density laser-plasma interactions at incident laser intensities of 5×1019W/cm2. Up to 1012 protons with energies greater than 2 MeV were observed to propagate through a 125µm thick aluminum target and measurements of their angular deflection were made. It is likely that the protons originate from the front surface of the target and are bent by large magnetic fields which exist in the target interior. To agree with our measurements these fields would be in excess of 30 MG and would be generated by the beam of fast electrons which is also observed. © 2000 The American Physical Society.