[en] A receiving system for a Thomson scattering experiment is described. This system includes a multichannel grating spectrometer designed for use with a high repetition rate Nd:YAG laser. Fiber-optic coupling bundles are used at the input and output ends. High throughput is maintained with large-diameter, low f-number grating and aspheric lenses. The detectors are high-responsivity, temperature-compensated avalanche photodiodes. Results of the calibration, including anti-Stokes Raman scattering, are presented. The spectrometer is designed to operate in the T/sub e/ range between 50 eV and 2 keV with a minimum electron density sensitivity of 1.6 x 10¹¹ cm^-3

[en] In this communication we show that the mechanism responsible for the optogalavanic effect in a hollow cathode discharge tube when the plasma is irradiated with a laser beam tuned on a non ionizing, allowed transition of the sputtered atoms is a global heating of the plasma. This heating results from a redistribution, via electron collisions, of the absorbed laser energy. Hence the associated laser induced ionization does not conserve the selectivity character of the irradiation. Furthermore we show that an optogalvanic spectroscopy based techniques is a promising approach to isotopic analysis of uranium. The value of the 235 isotopic abundance in natural uranium, found by this method, is in very good agreement with mass spectrometry determinations. This method appears to be much more accurate and reliable than the classical absorption or emission techniques of analysis. The calculated detection limit, in our experimental conditions, for an even uranium isotope is 10⁶ atoms/cm³. This corresponds to a 0.00015% abundance of this isotope

[en] Simultaneous detection of the optogalvanic effect and of the laser-induced intensity variations in emission lines in a uranium hollow-cathode discharge show that a part of the absorbed laser energy is transferred to all the species in the lamp by means of electron collisions. This transfer results in a global heating of the plasma and in an increase of ion and atom densities. From the measured nonisotopic selectivity of ion production associated with the optogalvanic effect, we conclude that impedance changes in the discharge are essentially due to the heating of the plasma. It follows that the optogalvanic effect is not a suitable scheme for isotopic enrichment by cataphoresis

[en] We have used optical pumping to produce a substantial ²³⁵U enrichment in the metastable levels of UI in the discharge afterglow of a hollow-cathode vapor generator. The measured isotope-enrichment factor for the level at 3800 cm^-1 is approximately 20

[en] Laser induced fluorescence from radiatively and collisionally populated states following optical pumping of the resonant transition at 5915 A has been used to investigate the hyperfine structure (hfs) of some /sup 235/U levels. From the fitting of the measured spectra, the hfs constants A and B were obtained for the levels at 6249, 23 543, 22 918, 22 862, and 22 754 cm^-1