Abstract
Absorption, reflection, and symmetry measurements have been made on spherical laser fusion targets for both single beam (highly non-symmet-ric), and four beam (more symmetric) irradiation, at incident laser energies of up to 250 joules. Optical, charged particle and x-ray measurement techniques are used to show the essentially symmetric be-havior of the multi-beam irradiation. A measure of the effectiveness of lateral heat conductivity is obtained from a comparison of symmetric and non-symmetric irradiation results. Greatpr thp 30% of the incident laser energy at an intensity of 1015-1016W/cm2 results in elevated plasma temper4tures. The energy deposited in high energy photons is less than 10-3 of the absorbed energy. No distinct high energy Ion com-ponent is observed and, in any case, less than a few percent of the absorbed energy resides in ions of energies >10keV/nucleon.
Time resolved optical diagnostics have uncovered the presence of an “after pulse” emitted from the plasma at the laser frequency but fol-lowing the trailing edge of the heating pulse.
