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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1407-1409 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The design and operation of a new vaporizing assembly used for Q-plasma sources are described in this article. The vaporizing system, consisting of two ovens and an effuser, is used to vaporize and direct atoms onto a hot ionizer plate. The hot plate, which may be of tantalum, tungsten, or rhenium, singly ionizes the atoms on contact. The main advantages of this new assembly, compared to previous designs, are the production of higher plasma densities and the control of the radial plasma profile. The heaters of the two atomic beam ovens are independently controlled and monitored so that the gradients of the radial plasma profile can be modified. Plasma production with two ion species can also be performed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 124-129 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A study of the application of high-order TM0m0 modes of a cylindrical cavity to the measurement of the density of a magnetized plasma column is presented. It is shown theoretically that judiciously chosen high-order modes have the potential advantages of both a wide operational range of densities, and a wide range for which a simple perturbation theory is valid. Furthermore, an experiment is described which shows that the TM060 mode can be excited with a sufficiently high Q value to allow accurate determination of the resonant frequencies, and hence plasma density. Favorable comparison between densities in the range 1010–1012 cm−3 measured by means of the resonant cavity technique and microwave interferometry is presented.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 2089-2102 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The design of a diffration grating used as an output coupler for a Fabry–Pérot resonator is presented. We then consider the problem of determining the distortion and the cross-polarization of the incident Gaussian beam. Different types of gratings and planes with straight or curvilinear grooves and elliptical, have been designed and built. The output pattern from a resonator using such a grating has been measured experimentally. We found that the elliptical grating generates the least distortion and cross-polarization. This result is attributed to the geometry of the grooves and is in excellent agreement with numerical calculations.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 3492-3500 
    ISSN: 1089-7674
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The operation of a 92 GHz quasi-optical gyrotron having a resonator formed by a spherical mirror and a diffraction grating placed in −1 order Littrow mount is presented. A power of 150 kW with a Gaussian output pattern was measured. The Gaussian content in the output was 98% with less than 1% of depolarization. By optimizing the magnetic field at fixed frequency, a maximum efficiency of 15% was reached.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 1171-1181 
    ISSN: 1089-7666
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A modulated high frequency wave is used to remotely excite low frequency oscillations in a linear, strongly magnetized plasma column. An electromagnetic wave is launched as an extraordinary mode across the plasma by an external waveguide in the upper-hybrid frequency regime f≈fUH≈fce≈8 GHz, with P≤2 W. By frequency modulating (at fFM≈1–60 kHz, with fci(approximately-equal-to)30 kHz) the pump wave, the resonant layer is swept radially across the profile and perpendicularly to the field lines at f=fFM. The resulting radial oscillation of the electron linear and nonlinear pressure can be considered to act as a source term for the ion wave. A localized virtual antenna is thereby created inside the plasma. Measurements of the ion dielectric response (interferograms and perturbed distribution functions) via laser-induced fluorescence identify the two branches (forward, or ion-acoustic-like, and backward, or Bernstein, modes) of the electrostatic dispersion relation in the ion cyclotron frequency range. By changing the modulation bandwidth, and thus the spatial excursion of the oscillating resonant layer, a control on the perpendicular wavelength of the excited mode can be exerted. In particular, the possibility of selective excitation of the ion Bernstein wave is demonstrated experimentally.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 1095-1100 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The development of a new Q-plasma source is described. Emphasis is given to the novel parts of the system which have been designed to produce long term, constant density plasmas with low fluctuation levels, as well as long machine operation time. Relevant plasma parameters are obtained by laser induced fluorescence which is used as a diagnostic on the barium plasma. Plasma densities are in the range of 108 cm−3 to 1011 cm−3, with an electron temperature of about 0.2 eV, and a perpendicular ion temperature of the same magnitude. The parallel ion temperature is one half the perpendicular value.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 1409-1411 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Contamination due to particles generated and suspended in silane rf plasmas is investigated. Powder is rendered visible by illumination of the reactor volume. This simple diagnostic for global, spatio-temporal powder dynamics is used to study particle formation, trapping, and powder reduction by power modulation.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    World journal of surgery 16 (1992), S. 1167-1170 
    ISSN: 1432-2323
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé Un foie de cadavre est divisible en deux transplants, par une séparation du foie droit et du foie gauche ou une séparation du lobe droit et du lobe gauche à droite de la scissure ombilicale. L'étude anatomique de 33 foies a permis d'établir les modalités idéales de partage des éléments portaux. Il faut sectionner préférentiellement la veine porte gauche, plus longue et plus constante que la veine porte droite, la branche droit de l'artère hépatique, plus volumineuse et plus constante que sa branche gauche, et le canal hépatique gauche compte tenu de la vascularisation de la voie biliaire principale. Pour utiliser la longueur de la veine porte gauche, il est nécessaire d'interrompre toutes ses branches destinées au segment I et donc de réséquer ce segment. Après une séparation du lobe droit et du lobe gauche à droite de la scissure ombilicale, le segment IV perd constamment la totalité de son apport veineux portal et doit être réséqué. Avant une division hépatique, une cholangiographie et une artériographie doivent être réalisées afin de mettre en évidence d'éventuelles variations anatomiques au cours d'une dissection étendue susceptible d'entrainer une dévascularisation des voies biliaires.
    Kurzfassung: Resumen Un hígado cadavérico es divisible en dos trasplantes al seccionarlo entre sus lóbulos derecho e izquierdo o al seccionarlo entre el segmento medial izquierdo y el segmento lateral izquierdo medial a la hendidura umbilical. Se realizó un estudio anatómico sobre hígados con el objeto de definir las bases ideales para la partición de los elementos portales. Es preferible seccionar la vena porta izquierda, que es más larga y más constante que la derecha, la rama derecha de la arteria hepática, más voluminosa y más constante que la izquierda, y el canal hepático izquierdo en razón de la vascularización del colédoco. Para poder usar la longitud de la vena porta izquierda es necesario seccionar la totalidad de sus ramas hasta el segmento I y luego resecar este segmento. Después de la sección entre el segmento medial izquierdo y el segmento lateral izquierdo medial a la hendidura umbilical, el segmento medial izquierdo siempre pierde toda su vascularización venosa portal y debe ser resecado. Antes de dividir el hígado se debe realizar colangiografía y arteriografía con el objeto de detectar variaciones anatómicas y evitar disecciones extensas que pueden poner en peligro la vascularización de los canales biliares.
    Notizen: Abstract A cadaver liver is divisible into two transplants by section between right and left lobes, or section between left medial segment and left lateral segment medial to the umbilical cleft. To establish the ideal basis of partition of the portal elements, an anatomic study of 33 livers was performed. It is preferable to section the left portal vein, longer and more constant than the right, the right branch of the hepatic artery, larger and more constant than the left, and the left hepatic duct because of the vascularization of the common hepatic duct. To use the length of the left portal vein, it is necessary to section all its branches to segment I and then to resect this segment. After a section between the left medial segment and the left lateral segment medial to the umbilical cleft, the left medial segment always loses its total portal venous vascularization and should be resected. Before a split-liver, cholangiography and arteriography should be performed to detect anatomical variations without performing an extensive dissection which may endanger the vascularity of the bile ducts.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1572-9680
    Schlagwort(e): competition ; leaf water potential ; plantation forestry ; soil moisture ; timber species
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract In Italy, new agroforestry cultural models could play an important role in the diffusion of plantation forestry timber species. We studied the stem growth rates and leaf water potentials (Ψ) of common walnut (Juglans regia L.), and gravimetric soil moisture (θDW) depletion during the third and fourth growing seasons in an agroforestry trial in central Italy. Since the establishment of experimental plots in 1992, walnut was intercropped with alfalfa (Medicago sativa L.), with or without polyethylene (PE) mulching along tree rows. By the end of the study period, the unmulched-intercropped walnut was almost 68% smaller in stem diameter and height than the sole-unmulched control, demonstrating walnut’s sensitivity to alfalfa competition. The competitive effect of alfalfa on walnut stem growth was effectively controlled/reduced by PE mulching. Stem growth rates of mulched-intercropped walnut were always lower than the control, but much higher (ca. 235% in stem diameter and height) than those of unmulched-intercropped walnut. The higher field performance of mulched-intercropped walnut compared to the un- mulched-intercropped treatment was associated with higher soil moisture and predawn and midday Ψ values during the summer’s driest periods. The presence of PE mulching was also associated with lower levels of soil moisture during the early and late growing season, but this did not negatively affect walnut Ψ and growth rates. These results suggest that in the climatic conditions of central Italy, competition for soil moisture between young common walnut trees and alfalfa can be substantially lowered, but not completely eliminated, by PE mulching.
    Materialart: Digitale Medien
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  • 10
    ISSN: 1434-601X
    Schlagwort(e): 23.20.Lv ; 23.20.Nx ; 27.60. + j
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Low-lying energy levels in124Ba have been investigated from124Laβ-decay by using He-jet technique. Spin and parity assignments have been deduced from internal conversion electron measurements. Aβ-vibrational band based on a second 0+ state has been identified. Experimental level energies have been compared with IBFA-2 calculations.
    Materialart: Digitale Medien
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