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  • 1
    Electronic Resource
    Electronic Resource
    Critical slowing down of nuclear growth along the liquid/liquid coexistence curve (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 859-861 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The growth rate of a second liquid phase is studied in demixing process of n-butoxyethanol/water mixtures. Following the liquid/liquid coexistence curve from far-off critical compositions to the critical point, the growth rate of the droplets slows down markedly. The values of the mutual diffusion coefficient D extracted from the growth rate data are found to scale approximately with a power law of the form D ∼|| (T − Tc)/Tc||0.79.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.462419
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  • 2
    Electronic Resource
    Electronic Resource
    Beam measurements on a CHORDIS ion source : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2604-2606 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present beam measurements which have been carried out using a CHORDIS ion source supplied with a modified extraction system. This system is designed to handle extraction voltages up to 60 kV. For beam diagnostics, a Faraday cup and a sector magnet have been used. Presented are measurements on beam current, mass, and energy spectra in dependence on various source parameters as gas pressure, arc voltage, and extraction voltage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142851
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  • 3
    Electronic Resource
    Electronic Resource
    Beam investigations at a multicusp ion source : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2607-2609 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In cooperation with the Lawrence Berkeley Laboratory, a multicusp ion source has been investigated. The goal of these investigations is to generate a nearly pure atomic nitrogen (N+) ion beam. To achieve this, the discharge chamber is divided into two parts of different plasma parameters by means of a filter magnetic field. As beam diagnostics, a bending magnet and a faraday cup have been used. Measurements of the beam current density and the ion composition for a wide range of discharge conditions have been performed. By using a Langmuir probe, we have performed measurements of electron temperature and electron density.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142852
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  • 4
    Electronic Resource
    Electronic Resource
    Atomic nitrogen ion beam from a pulsed duoplasmatron ion source : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2616-2618 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A duoplasmatron ion source fed with nitrogen usually produces a N+ fraction of approx. 60% in dc mode. In pulsed mode, the duoplasmatron ion source turns out to be a nearly perfect source for atomic nitrogen ions with a high fraction of more than 90% in the milliampere range. This is achieved by pulsing the arc discharge and not by use of any filter magnets. Parameters of operation will be given, such as the comparatively low gas inlet pressure and the arc current, which far exceeds the arc current in dc mode.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142855
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  • 5
    Electronic Resource
    Electronic Resource
    In situ calibration of neutron detectors on TEXTOR (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 1945-1952 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Neutron yield measurements are performed at the Jülich Tokamak experiment TEXTOR with different detectors located around the Tokamak and on center axis above the shielding roof. Due to the large structure of the machine and the extended diagnostic equipment, both virgin and scattered neutrons are detected. To prepare a Bonner sphere of appropriate response, the shape of the degraded neutron spectrum was determined with a spherical ionization chamber in situ. These investigations have been enlarged under quasi-real conditions at the accelerator facility of the Physikalisch-Technische Bundesanstalt in Braunschweig with a set of Bonner spheres used as a spectrometer. For the calibration the plasma neutron source is simulated by two point sources, 238Pu/B and 252Cf. The sources are moved around the TEXTOR vessel along the position of the magnetic axis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143309
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  • 6
    Electronic Resource
    Electronic Resource
    Gravity and shear flow effects on spinodal decomposition in single component fluids (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 758-759 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Results of experiments, carried out in space and on earth, are reported in which spinodal decomposition in a single-component fluid (SF6) is studied by small angle light scattering. Deformed circular light-scattering patterns are observed. They reflect deformation of density fluctuations by gravity effects and shear flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.465753
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  • 7
    Electronic Resource
    Electronic Resource
    Frankfurt EBIS development: Fundamental research and new applications : Proceedings of 5th international conference on ion sources (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1069-1071 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Fundamental questions of electron beam ion sources (EBIS) are studied using three different setups. Cryogenic classical EBIS: The limit of ion–ion cooling in EBIS devices operating near the space-charge neutralization limit has been studied experimentally. To investigate different degrees of compensation of the electron beam by highly charged ions, a hemispherical analyzer has been constructed including a novel deceleration optic for high resolution. Using its energy definition we tested different modes of ion transportation in our multipassage magnetic spectrometer, which can be operated chromatically as well as extremely dispersively: up to 200 passages could be obtained. EBIS without magnetic field: First results on ion production in the short trap at the very dense crossover of an electron beam (XEBIS) confined only inertially without the use of magnetic fields are presented. Normal conducting short EBIS: Using a normal conducting field of 0.8 T of 25-cm length an EBIS is under construction to study extremely short ion extraction of approximately 4 μs for single turn injection into a medical synchrotron for cancer therapy (MEDEBIS).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145065
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  • 8
    Electronic Resource
    Electronic Resource
    Liquid scintillation detectors for gamma and neutron diagnostic at TEXTOR and results of runaway and sawtooth oscillations (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2594-2598 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Time and energy resolved neutron and gamma measurements are performed at the TEXTOR tokamak with a fast liquid NE-213 scintillator. To distinguish between neutron and gamma (γ)-ray induced events, pulse shape discrimination is used. To suppress scattered radiation, the detector is installed in well-shielded collimators aligned radially or tangentially to the plasma current. Count rates up to 2–3×105 s−1 can be processed without considerable reduction of n/γ discrimination and without gain instability. To demonstrate the capability of this system, typical results are presented as obtained from plasmas in TEXTOR during sawtooth oscillations, runaway discharges, pellet injection, and neutral beam injection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144657
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  • 9
    Electronic Resource
    Electronic Resource
    Quantization error of slit-grid emittance measurement devices : Proceedings of 5th international conference on ion sources (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1462-1464 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Slit-grid emittance measurement devices usually do not scan the beam continously but in fixed linear (x) and angular (x') steps. Thus in an emittance measurement performed with a slit-grid system, the beam is represented by a number of phase space boxes with a constant area or volume determined by the linear and angular resolution. Considering the emittance as the area in the two-dimensional subspace (x,x') covered by the beam, the quantization error and its dependence on the resolution (linear and angular) as well as the influence of the beam parameters is discussed. Measuring the very low emittance of the high efficiency source (HIEFS) proved that the quantization error can be unacceptably high ((very-much-greater-than)100%). With an optimized measuring device, the normalized emittance came down from 10−1 to 3.6×10−3 π mm mrad. Finally, a typical misleading result of an emittance measurement, caused by the quantization error, is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144946
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  • 10
    Electronic Resource
    Electronic Resource
    Energy spectra of ions and electrons of a duoplasmatron : International conference on ion sources (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 493-495 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The energy distributions of ions and electrons extracted from a duoplasmatron ion source have been measured by a 127° cylinder spectrometer, providing information on the axial potential distribution in the source. The energy resolution of the spectrometer was about ±1 eV. Compared to measurements with Langmuir probes, this method has the advantage that the plasma potential is not disturbed. The energy spectrum of the extracted ions shows up to three peaks, which are related to different places of ionization in the source. The total energy spread is up to 100 eV. This energy spread can be influenced (down to 6 eV) by the potential of the expansion cup. Surprisingly, 90% of the extracted electrons are not created at the cathode but in the plasma of the intermediate electrode. This knowedge allows a better optimization of the source by independent regulation of gas pressure, intermediate electrode potential, and cathode potential. For optimum ionization of the working gas the potential of the intermediate electrode can be regulated so that the electron energy reaches the optimum value for the ionization in front of the anode and the energy and the intensity of the electron current is regulated by means of the potential of the expansion cup. These parameters strongly influence the beam quality.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141231
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