PLASMA TEMPERATURE IN OPTICAL-FIELD IONIZATION OF GASES BY INTENSE ULTRASHORT PULSES OF ULTRAVIOLET-RADIATION

Plasma electron temperatures from 3 eV to >1 keV have been measured or inferred in 1018 W cm-2 optical field ionization of helium and neon at electron densities ranging from 1017 to 1021 cm-3 by laser pulses of 350 fs duration and 248 nm wavelength. Increase of temperature with gas density is dominated at high densities by a combination of nonlinear inverse bremsstrahlung and stimulated Raman scattering heating which are identified as factors limiting progress to shorter extreme ultraviolet laser wavelength in recombination of optical field ionized plasmas. © 1995 The American Physical Society.