Optimization of a Ni-like X-ray laser at 13.9 nm pumped by 100 ps pulses

Since 1998, we are able to produce a saturated lasing emission in Ni-like silver at 13.9 nm, using short multi pulses (100 ps) combined with a low energy prepulse. This source is now very well characterized and ready to be used for the applications. By contrast with the Ne-like ions, we have round that it is not possible to obtain intense X-ray emission from Ni-like ions when using long pump pulses (600 ps). Simulations performed at the CEA confirm these observations. We will present a summary of the results of the simulations and the experiments on the Ni-like silver laser 13.9 nm, comparing in particular the role of the different pumping parameters.