ABSTRACT
We report reduction of the pump laser intensity necessary for an optical–field ionized xray laser using a preformed plasma scheme. Anomalous short wavelength emission has been observed in a plasma produced by irradiation of high–intensity subpicosecond KrF laser pulses into a preformed boron nitride plasma. The observed spectra indicated that the electron temperature of the plasma was much lower than that expected by collisional heating.
