Measurements on collisionally excited soft-x-ray lasers

We observed, for the first time to our knowledge, soft-x-ray 3p–3s lasing in neonlike zinc and arsenic in the wavelength interval 212–267 Å, with gain coefficients ranging from 2.0 to 5.4 cm−1. Also, spectral lines were observed in neonlike gallium at the wavelengths predicted for lasing. A single-beam, driving laser (λ = 1.05 μm) at pulse energies of up to 500 J, with rise times of ~0.6 ns and pulse durations of 1–2 ns, was used with slab targets. Time-integrated diagnostics were used. We discuss the refractive bending of the lasing beams, the importance of the rise time of the driving laser pulse, and the interferometric measurement of the electron density gradients and density distributions of the lasant plasma.