Soft-x-ray generation in a helium environment using laser-produced plasmas

Soft-x-ray radiation was generated by focusing the beam of a Q-switched Nd:glass laser on a steel target in a chamber filled with He at pressures of 10E-5 mbar less or equal than p less or equal than 500 mbar. The radiation at lambda less or equal than 1.5 nm was detected using a P-I-N diode behind a 25-mym Be foil. For He pressures p less 100 mbar and laser pulse energies less or equal than 2J, the soft-x-ray emission of the laser-produced plasma was reduced by less than 10% compared with the emission under high-vacuum conditions. The half-width tau(x-ray) of the soft-x-ray emission time was independent of p and of the same order as the laser pulse half-width tau LASER approximate 17 nsec. (IFT)