Development of a compact polarization analysis apparatus for plasma soft X-ray laser

Laser-driven plasma soft X-ray laser, XRL, at a wavelength of 13.9 nm is generated from nickel-like silver plasmas. The polarization state at an end station is considered to be vertically linearly polarized due to the reflections at some Mo/Si multilayer mirrors installed in the XRL beamline, but the detail has not been verified experimentally. To evaluate and control the polarization state, a compact polarization analysis apparatus to adapt for the XRL end station is developed. Two Mo/Si multilayer mirrors are fabricated and the polarization properties are evaluated by using synchrotron radiation, SR. As a preliminary test of the apparatus, the reflectivity of the multilayer is measured by the XRL and it shows good agreement with that by SR.