Spatial structure of an expanding laser plasma consisting of aluminum ions and nuclei

The angular structure characteristics of the expansion of multiply charged aluminum ions and nuclei were determined for the first time for a wide range of densities of radiation fluxes (10⁸–5·10¹³ W/cm²) reaching the target. The experimental results were generalized to a wide spectrum of masses and radiation flux densities and this made it possible to provide a description of the expansion of a laser plasma in vacuum. The phenomenon of "self-focusing" of beams of ions of maximum density, whose angle of expansion was 20–30° (symmetric about the normal to the target), was detected for the first time. This phenomenon and the results obtained should be useful in those cases where a sharp directionality of ion sources would be needed as, for example, in injection of ions into accelerators.