Method and apparatus for continuously generating laser plasma x-rays by the use of a cryogenic target

Abstract

In a method and an apparatus for continuously generating laser plasma X-rays, pulsed X-rays are continuously generated at a stable output level for a long period of time from plasma produced by converging and irradiating a repetitive-shot pulsed main laser beam having high peak power onto a target formed on a cryogenic target layer. The basic structure comprises a rotary element having a cylindrical surface excellent in heat conductivity and rotatable within a vacuum chamber. A cooling device supplies the rotary element with a cryogenic fluid to cool. A cryogenic material supply mechanism supplies a chemically inert cryogenic material having a gaseous phase at temperature. From the cryogenic material, a cryogenic target layer of a predetermined thickness is formed on the surface of the rotary element. A main pulsed laser irradiating device continuously generates the pulsed X-rays from the plasma generated by the main laser beam generator. A crater produced after the main laser beam is converged and irradiated is brought into contact with the cryogenic material in a gaseous phase during rotation of the rotary element to reproduce the cryogenic target layer. The auxiliary laser beam device generates a pulsed auxiliary laser beam under separate control and irradiates the beam to remove fine particle debris of the cryogenic target layer ejected from the converging irradiation spot after dissipation of the plasma so as to heat the fine particle debris to vaporize and eliminate the debris.