Focusing the beam of a compact, repetitively pulsed x-ray laser to study the interaction of radiation with metallic targets and x-ray reflectometry

The interaction of focused soft x-ray laser radiation with metallic targets was studied experimentally, The radiation of a capillary-discharge Ne-like Ar ion laser (lambda = 46.9 nm) with a repetition rate of I Hz was focused on the surface of metallic samples by using a spherical Si/Sc multilayer m irror. The radiation intensity at the target surface was far greater than t he threshold for laser ablation of the materials in use - aluminium, brass, and stainless steel. A study of the shape of laser craters in relation to the position of the caustic of the focusing mirror, combined with computer ray-tracing simulations, made it possible to determine the radiation intens ity distribution in the focal region of the mirror. The radiation energy de nsity in the 2 mu m central domain of the focal spot was 10(2) J cm(-2), an d the corresponding intensity was 10(11) W cm(-2). The reflectivity of a Si /Sc multilayer mirror was measured as a function of the angle of incidence of the radiation.