1,721,183 research outputs found
Stigmatic spectrograph with a 2-D CCD detector for soft x-ray observations of laser produced plasmas
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Polarisation Shift of Low-Z Balmer Lines in Laser-Produced Plasmas
No full textUsing laser-produced plasmas of high temperature and density the authors have investigated the possible shifts due to local plasma polarisation on the Halpha lines emitted by C VI and N VII. In contradiction with a number of theoretical treatments, they have found no evidence for shifts of the predicted magnitude. Whatever the plasma conditions the Halpha lines have been observed to be unshifted to within +or-0.02 AA corresponding to the estimated accuracy of the measurements. Results are discussed in the light of the existing theoretical treatments and are compared with similar investigations in the isoelectronic sequences
Evidence of Anomalous Multiplet Line Shapes in Optically Thick Laser-Produced, Plasmas
No full textWe report observations of anomalous line shapes for the transitions 2p−3d (2P−2D) emitted by the Li-like ions N(V), O(VI), F(VII) in laser-produced plasmas. These transitions are normally doublets but show completely different characteristics (e.g., triplet structures or invension of two-component intensity ratios) in the plasmas. The observed line profiles are accounted for in terms of opacity and Doppler effect produced by plasma expansion. This interpretation is independent of the particular transition involved, i.e., multiplet structures can generate more complicated features with various unexpected new components, anomalous intensity ratios, etc
Satellite Spectra from Laser-produced Plasmas of Be, B, C, N and O in He-like and Li-like Configurations
No full textSatellite lines near the resonance lines in He-like and Li-like configurations have been observed in laser-produced plasmas of Be, B, C, N, and O. The observations have been made with a grazing incidence spectrograph with spatial resolution. These lines have been identified and compared with the existing theoretical predictions. Their intensities have been measured relative to the accompanying resonance lines
C+ and C++ ion densities scaling in laser plasmas by ultraviolet photoabsorption spectroscopy
No full textWaste processing: New near infrared technologies for material identification and selection
No full textThe awareness of environmental issues on a global scale increases the opportunities for waste handling companies. Recovery is set to become all the more important in areas such as waste selection, minerals processing, electronic scrap, metal and plastic recycling, refuse and the food industry. Effective recycling relies on effective sorting. Sorting is a fundamental step of the waste disposal/recovery process. The big players in the sorting market are pushing for the development of new technologies to cope with literally any type of waste. The purpose of this tutorial is to gain an understanding of waste management, frameworks, strategies, and components that are current and emerging in the field. A particular focus is given to spectroscopic techniques that pertains the material selection process with a greater emphasis placed on the NIR technology for material identification. Three different studies that make use of NIR technology are shown, they are an example of some of the possible applications and the excellent results that can be achieved with this technique
Soft X-Ray Emission of Continua from Laser Produced Plasmas
No full textPlasmas produced irradiating plane targets of low Z elements with moderate energy (3–10 J) lasers emit considerable amounts of free-free and free-bound continua in the soft X-ray region (10–100 Å) of the spectrum. With intensity calibrated grazing incidence spectrographs an intensity of the order of 108 W sr–1 Å–1 cm–2 emitted by the densest portion of the plasma inside the crater formed at the interaction was determined. This is in good agreement with theoretical predictions for a plasma of predetermined parameters. In case of high Z elements the continuum emitted has a very smooth wavelength dependence
Fine Structure and Spectral Broadening of Balmer Lines in Laser-Produced Plasmas
No full textThe profiles of the Balmer lines emitted in a laser-produced plasma by the ions B4+ to F8+ have been observed. For the Balmer-α line the fine-structure components are broadened and partially merged by the Stark effect, the thermal Doppler broadening, and the motional Doppler shift. To these lines a simplified model for an expanding plasma, used previously for the analysis of the Lyman lines of the same ions, has been applied. The results are in very good agreement with the observations, showing the overall validity of the interpretation. The various broadening mechanisms have been unfolded and in particular for the range of electron densities considered here a transition between the weak- and strong-field approximations for the Sark broadening is evident
Photoionization and Double Excitation Spectrum of Be 2+
No full textThe photoionization cross-section of Be2+ has been measured in the range from threshold at 154 eV up to 420 eV. The value at threshold of [1.4 ± 0.2] × 10−18 cm2 is in good agreement with theoretical predictions. The method used was that of absorption using two laser produced plasmas. The doubly excited resonance 2s2p 1p0 at 281.25 ± 0.07 eV has been observed and its Fano profile measured
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