X-RAY FIELD ASYMMETRY EFFECT ON THE TIME OF NEUTRON GENERATION IN EXPERIMENTS WITH INDIRECT DRIVE TARGETS

摘要

The investigations of the effect of controlled X-ray field asymmetry on the compression degree and the neutron yield in the targets of indirect (X-ray) drive were performed in 1998 at ISKRA-5 facility. The field asymmetry was induced by shift the central capsule (microballoon) with respect to the center of spherical box-converter. The experiments demonstrated neutron yield reduction with increasing of asymmetry degree. In parallel with this fact, shifting of microballoon about central position caused the rise of compression time, which was determined by indirect method using the compressed region X-ray luminescence. Our simulations used 2D code MIMOSA ND showed that theoretically calculated asymmetric X-ray field allows give satisfactory explanation for the experimentally observed neutron yield reduction in relation to the microballoon shift value. The simulations showed also that there is the time delay of neutron generation relative to the self generated X-ray pulse. It was interestingly to perform the direct measurements of the time moment of neutron yield in experiment. For these purposes authors designed the special diagnostic.