2-DIMENSIONAL BEAM CHARACTERISTICS OF TRIPLE-PULSE PUMPING A NE-LIKE GE SOFT-X-RAY LASER AT 19.6 NM

We have demonstrated the triple-pulse pumping of a Ne-like Ge soft-x-ray laser at 19.6 nm in amplified spontaneous emission (ASE) and amplifier modes. Two-dimensional beam characteristics have been investigated with a curved slab target. In comparison with the double-pulse pumping scheme, the increase of output intensity of the soft-x-ray laser has been obtained with the triple-pulse pumping scheme in the ASE mode. The amplifier mode of the Ne-like Ge soft-x-ray laser has been achieved with the triple-pulse pumping scheme. Significantly different beam intensity distributions between the horizontal (x) and vertical (y) directions have been observed. A hydrodynamic simulation coupled with ray-trace calculations has been made with the curved slab targets. The ray-trace calculations show different beam propagation in the x and y directions due to different electron density distributions. The beam divergence has also been calculated in the ASE and amplifier modes and compared to the measured beam divergence. Based on the experimental and simulation results, we conclude that there are different beam characteristics in the two directions. There is beam guiding in the x direction but not in the y direction.