Uniformity and isotropy of the fast ion emission at a target surface irradiated by a CO2 laser

Filtered pinhole imaging is used to characterize spatially the fast ion emission at the target surface irradiated by a CO2 laser in a planar geometry. The bulk of the fast ions is found to be fairly well correlated with the lateral transport of hot electrons in the target plane, i.e., a large concentration of rather low-energy ions near the focal spot with total ion emission over a very large area. Higher-energy ions show large emission nonuniformities and very small local cone angles somewhat difficult to explain.