EXTREME-ULTRAVIOLET LINE EMISSION AT 24.7 NM FROM LI-LIKE NITROGEN PLASMA PRODUCED BY A SHORT KRF EXCIMER-LASER PULSE

Recently using KrF high power laser (248 nm; 350 fs; 5.0x10(16) W/cm(2 )) in the Rutherford Appleton Laboratory an experimental search for re combination extreme ultraviolet (XUV) laser action in Li-like nitrogen ions was performed. To understand the experimental results of line em ission at 24.7 nm in the 3d(5/2)-2p(3/2) transition of the Li-like nit rogen ion a simulation was undertaken using a one-dimensional Lagrangi an hydrodynamic code. From the simulation results, we confirmed that t here was nonlinear dependence of spectral line emission on the gas den sity which was well matched to the experimental results. Only a six ti mes increase of the 24.7 nm emission intensity was obtained when the p lasma length was increased 1000 times from 1 mu m as an optically thin case to 1 mm. Also, the spatial profile of the electron density and t emperature was obtained and the electron temperature was about 40-50 e V which was too high for the optical field ionization x-ray lasing. We could not find evidence of x-ray laser gain. (C) 1996 American Instit ute of Physics.