Experiment of Si target ablation with soft X-ray laser operating at a wavelength of 46.9 nm

We successfully ablated the Si target by the focused beam of capillary-discharge pumped laser at 46.9 nm. The laser of ∼50 μJ was focused by the sagittal surface of the cylinder mirror at grazing incidence. Fluences of the focused beam were varied by changing the distance between the mirror and target, and clear ablation patterns were obtained. The shapes of the patterns were consistent with the results simulated by ZEMAX software. The irradiance of the focal spot was simulated as well. Each pattern was ablated by 200 shots and the sampling distance between any two contiguous ablation positions was 0.7 cm. The peak value of energy density of the focal spot was estimated to be 7.48×10 ^-3 J/cm ². According to the ablation pattern, the focal point of the mirror was determined. The experiment provides reliable data and focusing method for interaction of X-ray laser with solid target.