Spatial separation of EUV emission and energetic ions by use of double-laser-pulse irradiation

We have demonstrated the spatial separation of extreme ultraviolet (EUV) emission and energetic tin (Sn) ions as debris from a laser-produced plasma (LPP) with a double-laser-pulse irradiation scheme based on a plasma X-ray laser configuration. We used two Nd:YAG lasers operating at a wavelength of 1064 nm for pre- and main pulses. The pre-pulse at a laser intensity of 2×10⁸ W/cm² was irradiated to the Sn solid planar target to produce a pre-plasma. After 20 ns from pre-pulse irradiation, the main pulse at a laser intensity of 2×10¹¹ W/cm² was irradiated in a tangential direction to the pre-plasma. We observed the angular distributions of EUV emission and energetic ions using an X-ray diode and a Faraday cup. The EUV was slightly emitted toward the main pulse. On the other hand, energetic ions were emitted toward the prepulse side. Under similar conditions, charge-separated energetic Sn ions were measured using an electrostatic energy analyzer (ESA), and the maximum kinetic energy and maximum valence were reduced.