A two element magneto-optical trap (MOT) for Na and Li-7 or Li-6 is used to cool and trap each of them separately. A fraction of the cold atoms is maintained in the first P-2(3/2) excited state by the cooling laser. These excited state atoms are ionized by laser light in the near-UV region, giving rise to a smaller number of trapped atoms and to different loading parameters. Photoionization cross-sections were derived out of these data. They are in reasonable agreement with data previously obtained using thermal samples and with theoretical predictions

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Electric field emissions at frequencies of (n + ½)fce have been generated in a large‐scale electron beam experiment in the giant NASA vacuum facility in Ohio. These emissions arise when a contrastreaming beam configuration exists, the primary beam consisting of monoenergetic electrons (50 eV to 5 keV) and the other beam of lower‐energy ‘backscattered’ secondary electrons. It is suggested that the same mechanism could also be the source of the observed emissions at auroral latitudes. In the absence of the beam‐beam instability, weak oscillations were observed at the plasma frequency. In the latter case no significant modifications of the primary beam velocity distribution occurred, and the beam configuration is adequately described by single‐particle motion in the ambient magnetic field.

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