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Using gas targets, $K$ x-ray cross sections have been measured as a function of projectile charge state in nearly symmetric collisions for highly ionized S and Cl ions at a velocity comparable to that of the $K$-shell electrons. For bare nuclei, the projectile cross sections are accurately described by the cross section for capture to excited states calculated in a Brinkman-Kramers approximation and normalized by a single scaling factor. With lower-charge-state incident ions, the total $K$-vacancy cross section is in good agreement with the $2p\ensuremath{\pi}\ensuremath{-}2p\ensuremath{\sigma}$ cross section for rotational coupling.

Polarization fractions have been measured for K X-rays emitted by energetic fluorine ions passing through helium gas. A strong monotonic charge state dependence is found, increasing to an observed polarization of ∼ 30% for highly charged ions.

The propagation of nanosecond CO2 laser pulses in high-power high-gain amplifiers has been well understood for several years.1-4 However, the amplification of subnanosecond pulses has not been thoroughly investigated. In a previous experiment5 on the propagation of 570-psec pulses in a low-gain TEA laser, a significant discrepancy between experiment and theory was observed. It was found that the 570-psec pulses broadened to 880 psec upon amplification, whereas theory predicted that they should have narrowed to 370 psec.