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Harmonic seeded operation of a neon-like titanium plasma-based soft x-ray laser is described. The plasma amplifier is pumped with a variation of the grazing incidence technique involving a fast and localized ionization step. We discuss its effect on gain dynamics by measuring the amplifying factor as a function of the delay between pump pulse and harmonic seed. Two different regimes are pointed out, following the pumping scheme used. For one of them, a delay in the gain generation compared with the pumping laser pulse is observed.

An alternative, novel multiple pulse generation scheme was implemented directly after the optical compressor output of an x-ray pump laser. The new method uses a polarization sensitive thin film beam splitter and a half-wavelength wave plate for tuning the energy ratio in the multiple short pulses. Based on this method, an extensive study was made of the running parameters for a grazing incidence pumped silver x-ray laser (XRL) pumped with a long pulse of 145 mJ in 6 ns at 532 nm and up to 1.45 J in few picoseconds at 810 nm. Fivefold enhancement in the emission of the silver XRL was demonstrated using the new pump method.

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