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[en] The Thomson-scattered spectra observed at the experiments TORTUR 2 and 3 show systematic deviations with respect to a gaussian profile. In order to study these spectra in more detail a 20-channel spectrometer has been designed and constructed to replace the present 10-channel apparatus. In the former instrument the analysed spectrum was directed to the photomultiplier by means of a fibre-optic array. The transmission of the new spectrometer has been increased by a factor 2.5 up to 45% by using wavelength selection mirrors instead of fibre optics. Electron temperatures and densities can be determined with a 5% error at values of 800 eV and 5x1019 m-3. The detection limit of the diagnostic has been improved to nsub(e) approx. 3X1018 m-3 at Tsub(e) approx. 500 eV. (Auth.)
[en] A scalable setup using injection by frequency conversion to establish a multipassing cavity for noncollective Thomson scattering on low density plasmas is presented. The cavity is shown to support >10 passes through the target volume with a 400% increase in energy on target versus a single-pass setup. Rayleigh scattering experiments were performed and demonstrate the viability of the cell to study low density plasmas of the order of 1012-1013 cm-3. A high-repetition, low-energy, single-pass Thomson scattering setup was also performed on the University of California, Los Angeles Large Plasma Device and shows that the multipass cavity could have a significant advantage over the high-repetition approach due to the cavity setup's inherently higher signal per shot.
[en] Studied in this paper is the influence of Rayleigh scattering on the ion feature of the Thomson scattering spectrum from a partially stripped plasma. The result shows that the profile of the scattering spectrum is nearly the same as that of Thomson scattering with inclusion of Rayleigh scattering, but the intensity of the scattering signal may be remarkably different from that of Thomson scattering
[en] A method of generalized Bethe potential taking exact account of all higher order terms of the Bethe potential, is proposed for intensity calculations of reflection electron diffraction. Test calculations concerning this method are given. Comparisons of intensity curves using this method with those accurately calculated show that this method is applicable for economizing the number of diffracted beams used in intensity calculations. (auth.)
[en] Moshinsky's work on diffraction in time is recognized as a particular case of monoenergetic, quantum dispersion process. Diffraction in time is extended to include new initial conditions, which under free evolution exhibit temporal quantum interference patterns in close analogy to spatial diffraction patterns found in optics. We show that free propagation of states, which initially are stationary states of infinite potential wells, diffract in time similarly as a plane wave by a double slit. We introduce the concepts of mass transport by transient Fraunhofer and Fresnel dispersion currents
[en] Based on the Fresnel approach discussed in a previous article the S-matrix for nuclear elastic scattering is factorized into an infinite product, the n-th term of which is essentially given by (n -- 1) -fold commutators of the interaction potential at n different z-coordinate positions. A subsequent cumulant expansion expresses the Fresnel phase shift as an infinite sum of many-body clusters. In contrast to eikonal-type expansions each term of this sum contains contributions of all orders in the inverse wave number. Because of this feature the present expansion is useful for scattering from light nuclei over a wide range of energies and scattering angles
[en] X-ray resonant diffraction can be applied in structural chemistry studies on powder samples. It enables an important limitation of powder diffraction to be overcome. This limitation is related to the low ability of powder diffraction to differentiate elements with close atomic numbers when they occupy the same or close crystallographic sites (mixed occupancy case) and also to discriminate cations with different valence states in different sites. However the resonant effect usually has a second order influence on the measured intensity. As a consequence, the efficiency of this method directly implies the need for excellent quality data collection and has generally been better assessed on elements present in single phase powder samples. In recent years, instrumental developments have been made in synchrotron radiation facilities which allow easier use of resonant powder diffraction for site-specific contrast and valence i.e. oxidation state analyses. Moreover, resonant contrast diffraction tools also have been proposed for better visualization of the anomalous effect both in direct and reciprocal space by using differences between electron density maps or diffraction patterns. Finally the potentialities of this technique for 'de novo' structure solution on macromolecular systems are mentioned. (authors)
[en] A polychromator has been designed and constructed for the measurement of the electron temperature with high spatial resolution by Thomson scattering in the stabilized z-pinch EXTRAP. The design is centered on the use of low-loss silica single fibres of 0.4 mm core diameter. The dispersive element is an aberraion corrected concave holographic grating, specially designed to image the input fibre face onto the output fibre array with high efficiency. Very good stray light rejection is achived due to the grating being the single optical element in the polychromator. (author)
[en] A useful formulation of potential scattering is presented in terms of multiple scattering series. This formulation starts from an approximation of the exact Green function in momentum space by the sum of two propagators (forward and backward propagators). This replacement leads naturally to both the forward and backward approximation in the same way. The Fresnel diffraction is incorporated with the to-and-fro motion (reflection) in a potential. High-energy corrections are also presented to the eikonal approximation. This formulation permits a straightforward application to scattering off a composite system, and has a close relationship to the Glauber approximation
[en] Problems are an important instrument for teachers to mediate physics content and for learners to adopt this content. This collection of problems is not only suited to traditional teaching and learning in lectures or student labs, but also to all kinds of new ways of teaching and learning, such as self-study, long-distance teaching, project-oriented learning and the use of remote labs/web experiments. We focus on Rutherford's scattering experiment, electron diffraction, Millikan's experiment and the use of pendulums to measure the dependence of gravitational acceleration on latitude. The collection contains about 50 problems with 160 subtasks and solutions, altogether 100 pages. Structure, content, range and the added value of the problems are described. The whole collection can be downloaded for free from http://rcl.physik.uni-kl.de.