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  • 1995-1999  (96)
  • 1930-1934  (7)
  • 1905-1909  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Azimuthally symmetric pseudosurface and helicon wave propagation in an inductively coupled plasma at low magnetic field (1998)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 5 (1998), S. 3135-3142 
    Details
    ISSN: 1089-7674
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The mode transition from a capacitively coupled mode (E mode) to an inductively coupled mode (H mode) was observed in an inductive Ar plasma source by applying an axially uniform low B field. The applied fundamental rf was 13.56 MHz and many harmonic components were observed. A beat and standing wave patterns of azimuthally symmetric (m=0 mode) first and second harmonic pseudosurfaces and helicon waves were measured at various densities (n∼9.0×1010–2.2×1011 cm−3) and B fields (12–28 G). Wave propagation mode changes, from pseudosurface to helicon waves and from helicon to pseudosurface waves, were observed at critical conditions, ωc/ω〉3.0 and n∼2.2×1011 cm−3. © 1998 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.873040
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  • 2
    Digitale Medien
    Digitale Medien
    Experimental investigation of the interaction of 100 TW laser with solid targets (abstract) : Proceedings of the eleventh topical conference on high temperature plasma diagnostics (1997)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 847-847 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We report on the first plasma experiments with the 100 TW laser at LLNL. We have experimentally investigated the interaction of 1 μm, 40 J, 400 fs, 5×1019 W/cm2 laser pulses with multilayer solid targets. Various diagnostics were used to characterize this interaction. An x-ray pinhole camera monitored laser spot size and plasma location on target. Part of the laser beam was split off to probe the density scale length of the preformed plasma. An optical system for Schlieren photography was designed to record the images of plasma with electron density gradients as low as 1021 cm−4 with characteristic scale length of 10 μm. The range of electron densities was 1018–2020 cm−3. CR-39 plastic track detectors were employed to measure the fast ion blowoff from the plasma. Using a foil-filter technique the proton energy spectrum up to 6 MeV was measured. It was found that the high energy tail usually had a narrow (FWHM ∼10°) cone of expansion. Energy conversion to the fast ions (above 0.5 MeV) was estimated to be ∼0.3%–1% of laser energy. In addition, charge-coupled devices were used for detecting characteristic K α emission caused by fast (〉1 MeV) electrons. (See article by K. Wharton for further discussion of the fast electron measurements.) Estimated fast electron yield ∼3%.© 1997 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1148452
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  • 3
    Digitale Medien
    Digitale Medien
    Superconducting magnetic shields for SQUID applications (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 4562-4568 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We investigate the shielding of superconducting and μ-metal forms in axial and transverse directed background magnetic noise fields. Analytical expressions are obtained for the improvement in signal-to-noise ratio obtained by placing a superconducting disk in the presence of a dipole source and a uniform noise field. Axial and transverse shielding factors are then compared for identical superconducting and μ-metal cylinders. The signal-to-noise ratio is found to be infinite at certain points inside a superconducting cylinder as well as a superconducting cylinder with a central partition. Shielding factors obtained here are relevant to SQUID measurements of small dipole source fields in the presence of large background noise fields such as those encountered in biomagnetism and nondestructive evaluation. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150113
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  • 4
    Digitale Medien
    Digitale Medien
    Sheath physics study using the divertor materials evaluation system (DIMES) on DIII-D : Proceedings of the tenth topical conference on high temperature plasma diagnostics (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 827-829 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A set of 19 dome-shaped divertor Langmuir probes similar in design to probes used in JET and JT-60 has been used successfully in DIII-D to measure the divertor electron temperature, particle flux, and floating potential. A comparison of the power flux using IR cameras with the particle flux and electron temperature from the probes using collisionless sheath theory has indicated that the particle flux to the divertor surface may be strongly modified by collisions within the magnetic sheath. In order to study this effect, a set of probes have been designed that can be inserted into the divertor plasma using DIMES. Two dome-shaped probes compare fluxes intercepted both above and within the magnetic sheath of the divertor surface. In addition, a third probe oriented normal to the magnetic field is used to verify the projected area of the probe surface. The probe design accommodates parallel power fluxes up to 50 MW/m2 for 30 ms, allowing for the study of beam-heated plasmas in DIII-D. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1146236
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  • 5
    Digitale Medien
    Digitale Medien
    Measurements of fast electrons produced in solid targets by laser intensities of 5×1019 W/cm2 (abstract) : Proceedings of the eleventh topical conference on high temperature plasma diagnostics (1997)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 847-847 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We report on experiments using the 100 TW laser at LLNL (40J, 400 fs, 5×1019 W/cm2 focal intensity) and planar multilayer targets (Mo/Sn) to study the generation and transport of electrons with MeV energies. Such fast electrons are of prime importance to many proposed applications, e.g., the fast ignitor fusion concept. X-ray emission spectroscopy is used to study the electron transport. Characteristic K α photon emission produced by the fast electrons in the front (Mo) and rear (Sn) layers of the target is measured with a charge-coupled device detector (single photon counting mode) to infer the electron energy deposition. The electron energy spectrum is measured by varying the thickness of the Mo layer to attenuate the electrons by different amounts. Penumbral imaging of the K α emission is used to give information about the angular distribution of the fast electron emission. Details of the measurement techniques and experimental results will be discussed and compared with modeling calculations.© 1997 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1148451
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  • 6
    Digitale Medien
    Digitale Medien
    Granulite facies metamorphism in the Mallee Bore area, northern Harts Range: implications for the thermal evolution of the eastern Arunta Inlier, central Australia (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of metamorphic geology 15 (1997), S. 0 
    Details
    ISSN: 1525-1314
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Geologie und Paläontologie
    Notizen: The Mallee Bore area in the northern Harts Range of central Australia underwent high-temperature, medium-to high-pressure granulite facies metamorphism. Individual geothermometers and geobarometers and average P-T calculations using the program Thermocalc suggest that peak metamorphic conditions were 705–810C and 8–12 kbar. Partial melting of both metasedimentary and meta-igneous rocks, forming garnet-bearing restites, occurred under peak metamorphic conditions. Comparison with partial melting experiments suggests that vapour-absent melting in metabasic and metapelitic rocks with compositions close to those of rocks in the Mallee Bore area occurs at 800–875C and 〉9–10 kbar. The lower temperatures obtained from geothermometry imply that mineral compositions were reset during cooling. Following the metamorphic peak, the rocks underwent local mylonitization at 680–730C and 5.8–7.7 kbar. After mylonitization ceased, garnet retrogressed locally to biotite, which was probably caused by fluids exsolving from crystallizing melts. These three events are interpreted as different stages of a single, continuous, clockwise P-T path. The metamorphism at Mallee Bore probably occurred during the 1745–1730 Ma Late Strangways Orogeny, and the area escaped significant crustal reworking during the Anmatjira and Alice Springs events that locally reached amphibolite facies conditions elsewhere in the Harts Ranges.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1525-1314.1997.tb00639.x
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  • 7
    Digitale Medien
    Digitale Medien
    Kerion — a case report (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental dermatology 20 (1995), S. 0 
    Details
    ISSN: 1365-2230
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: We describe a 6-year-old girl with severe tinea capitis, who required several months of systemic treatment with griseofulvin, before her condition started to improve with eventual partial hair regrowrh.Kerion refers to the severe inflammatory reaction that occurs in some cases of fungal infection of the hair or hair follicles. The word is derived from the Greek, meaning honeycomb. There is usually a painful, inflamed area studded with pustules, which eventually forms nodules and sinuses. The condition is self-limiting, but even with treatment permanent scarring may ensue.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2230.1995.tb01360.x
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  • 8
    Digitale Medien
    Digitale Medien
    Formation and growth of black spots in organic light-emitting diodes (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 6002-6007 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We report electroluminescence (EL) degradation studies of thin-film organic light-emitting diodes under ambient conditions. Bilayer organic ITO/TPD/Alq3/Mg/Ag devices were studied via EL and photoluminescence (PL) microscopy. In situ imaging of device luminescing areas and measurement of sample luminance were performed, allowing for a detailed study of black spot formation and luminance reduction under constant voltage stress conditions. Post-stress devices were further characterized using PL microscopy, and it was found that black spots result from delamination of the metal at the Alq3/Mg interface initiated by pinholes on the cathode, caused by substrate defects. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.363598
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  • 9
    Digitale Medien
    Digitale Medien
    Precipitate formation in carbon-doped base of InGaP/GaAs heterojunction bipolar transistors grown by low-pressure metal organic chemical vapor deposition (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 2993-2995 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The effect of intermediate temperature annealing on the carbon-doped base region of InGaP/GaAs heterojunction bipolar transistors (HBTs) was studied. This work shows that after annealing at only 600 °C a sample doped at 5.5×1019 cm−3 displays carbon precipitation. InGaP/GaAs HBT structures were grown for the annealing study. Hall measurements were used to measure hole concentration. Atomic force microscopy was employed to identify carbon precipitation. The annealing process not only removes hydrogen from the base but also creates carbon precipitates. The dc current gain measurements imply that the carbon precipitates increase base recombination. These results are very important in the growth and postgrowth annealing of high gain HBTs. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.123990
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  • 10
    Digitale Medien
    Digitale Medien
    Minimization of ion micromotion in a Paul trap (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 5025-5033 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Micromotion of ions in Paul traps has several adverse effects, including alterations of atomic transition line shapes, significant second-order Doppler shifts in high-accuracy studies, and limited confinement time in the absence of cooling. The ac electric field that causes the micromotion may also induce significant Stark shifts in atomic transitions. We describe three methods of detecting micromotion. The first relies on the change of the average ion position as the trap potentials are changed. The second monitors the amplitude of the sidebands of a narrow atomic transition, caused by the first-order Doppler shift due to the micromotion. The last technique detects the Doppler shift induced modulation of the fluorescence rate of a broad atomic transition. We discuss the detection sensitivity of each method to Doppler and Stark shifts, and show experimental results using the last technique.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.367318
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