Application of a refractive bubbles-in-capillary x-ray lens to X pinch experiments

A new type of x-ray refractive lens, the refractive bubbles-in-capillary lens ~RBC lens!, for plasma diagnostics is presented. The lens consists of a glass capillary filled with a large number of biconcave microlenses. The fabrication technique for the lens is described. It is shown that the microlenses have a spherical shape and can focus x-ray radiation with photon energies E .4 keV. Ray-tracing and analytical calculations of lens properties have been performed and have predicted high efficiency and good spatial resolution for RBC lenses. Real lenses were tested using Cr Ka x-ray radiation (l52.29 Å), and spatial resolution of about 10 mm was obtained. In plasma experiments, x-ray radiation from a Ti X pinch (l52.62 Å) was focused by a lens with 35 bubbles in a 100 mm diam capillary ~focal length of about 8 cm! to a spot with diameter less than 6 mm. The shape of the hot plasma could be seen. Possibilities for RBC lens applications to plasma measurements are discussed