Spatial coherence measurement of 13.9 nm Ni-like Ag soft X-ray laser pumped by a 1.5 ps, 20 J laser

In this paper, we report the first measurement of the time-integrated spatial coherence of the Ni-like Ag X-ray laser at 13.9 nm pumped by a 1.5 ps, 20 J Nd glass laser, in which the transient collisional excitation (TCE) pumping scheme is realized. The time-integrated complex coherence factor (CCF) of the X-ray laser has been determined from partially coherent diffraction patterns of a multislit array placed 1 m away from the X-ray laser source. The transverse coherence lengths in the directions horizontal and vertical to the Ag target surface are estimated respectively to be within 110 pm to 140 mum at a position 1 m from the X-ray laser source. We tried to explain the profile of the CCF with a quasi-monochromatic incoherent source model with various profiles.