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  • 1
    Digitale Medien
    Digitale Medien
    Development of a dc low pressure D− surface-conversion source using a 10-cm-diam solid barium converter : Proceeding of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2705-2707 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A D− surface-conversion source using a solid barium converter is designed for steady-state operation to produce 200 mA of D−. A similar ion source of twice the size as the one discussed here will meet the requirements set by the present US-ITER neutral beam injector design. Among the possible types of ion sources being considered for the US-ITER neutral beam design, the barium converter surface-conversion source is the only kind that does not use cesium in the discharge. This absence of cesium will minimize the number of accelerator breakdowns.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1142829
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  • 2
    Digitale Medien
    Digitale Medien
    Testing of an advanced "volume'' H− source and preaccelerator (1991)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 62 (1991), S. 1521-1526 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: In testing a cesiated volume-production negative ion source, we have obtained 75 mA of H− beam current in a 270 ms pulse length delivered downstream of the 87 keV preaccelerator. Optimum pressure in the source was less than 8 mT and the electron-to-ion ratio in the beam was less than 4. With future improvements in the electron trap, it is anticipated that higher H− current can be obtained by operating with a higher discharge power and a lower plasma electrode bias.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1142480
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  • 3
    Digitale Medien
    Digitale Medien
    Acceleration of 100 mA of H− in a single channel electrostatic quadrupole accelerator (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 3864-3868 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Neutral beams for the next generation tokamaks will be based on multiampere negative ion beams with a beam energy of about 1.0 MeV and pulse lengths of a thousand seconds. High intensity dc beams at these levels of beam energy will require extensive development in electrostatic accelerators. At Lawrence Berkeley Laboratory, a two-module electrostatic quadrupole (ESQ) accelerator was built to accelerate ions to 200 keV. In this experiment, up to 100 mA of H− beam current was obtained from a Japan Atomic Energy Research Institute cesiated volume source using a multiaperture preaccelerator which merged 19 beamlets into a single circular beam at the entrance to the ESQ accelerator. The H− beam was accelerated by the ESQ to accelerate 200 keV without any significant beam loss or emittance growth. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1145450
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  • 4
    Digitale Medien
    Digitale Medien
    Development testing of the U.S. common long pulse source at 120 kV (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2357-2365 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The U. S. magnetic fusion energy program has developed a single design, long-pulse neutral beam source for TFTR, MFTF-B, and DIII-D. The arc is a very compact axial magnetic line cusp. The accelerator is an actively cooled tetrode with water-cooled grid tubes of shaped molybdenum forming "slot'' beamlets. DIII-D and MFTF-B configurations have an 80-kV accelerator gap, with a 12×18 cm aperture, and a 10-m "module'' focus. TFTR modules are unfocused, with a 120-kV gap and 12×43-cm mask. The first CLPS was tested in the TFTR configuration, at 120 kV, 2s. Optimum current was 73 A, or 1.76 μpervs (deuterium), with 80%–85% atomic fraction. Optimum divergence of ions plus neutrals was 0.4° parallel to the slots, and 0.7° perpendicular to the slots (1/e half-angle). The combination of an axial cusp magnetic bucket and slot accelerator apertures gives the common long pulse source about twice the beam power per unit cross section of other long pulse sources, plus lower divergence in the direction parallel to the slots.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1139961
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  • 5
    Digitale Medien
    Digitale Medien
    120-kV testing of a 10×40-cm prototype of the U. S. common long pulse neutral beam source (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 2714-2719 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The 10×40-cm long pulse neutral beam source developed at Lawrence Berkeley Laboratory has been selected as the prototype for the design of the U. S. common long pulse source to be used on tokamak fusion test reactor (TFTR), Doublet-III, and mirror fusion test facility (MFTF-B). The long pulse source consists of a magnetic line cusp bucket with an actively cooled backplate electron dump and a four-grid accelerator using slot apertures and water-cooled molybdenum rails. Deuterium testing of the long pulse source at 120 kV and 53 A and with a 2-s pulse length has been completed on the neutral beam engineering test facility, including an 8-h 100-shot test to demonstrate the durability and reliability of the source. Maximum 2-s beam parameters obtained (not simultaneously) are 125 kV, 58 A (deuterium), and 7.1 MW. Beam pulse length has been extended to 5 s at 120 kV. Atomic species fractions in excess of 80% have been obtained, with a beam divergence (full energy, 1/e half-angle) of approximately 0.8×0.4°. Calorimetric measurements on the accelerator grids and backplate electron dump indicate heat loads consistent with predictions and within the design limits of the source. This testing has verified the design of the source and its ability to exceed the basic performance requirements.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1139082
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  • 6
    Digitale Medien
    Digitale Medien
    Low-energy injector design for SSC : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2738-2740 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: An injector is being designed for SSC that will deliver 30 mA of H− at 35 keV, matched to the RFQ input. The H− ions are produced by a new rf-driven multicusp source that uses no cesium. The ions are extracted by a high-perveance accelerator designed to handle the large electron content of this type of source. The low-energy beam transport system (LEBT) uses electrostatic focusing; gas-neutralized magnetic focusing is ruled out because pulse lengths (7–35 μs) are shorter than plasma buildup times and because pulse intervals are longer than plasma decay times. Plasma buildup is prevented by the LEBT electric fields, so the system is noise free and stable. The advantages of electrostatic LEBTs were demonstrated by a previous design tested at LBL, which showed negligible emittance growth, confirming the results of computer modeling. The object of our new LEBT design is to preserve the emittance of the rf-driven source, which is less than 0.01 π mrad cm (normalized rms), and thereby produce a beam well within the SSC RFQ acceptance of 0.018 π mrad cm.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1142840
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  • 7
    Digitale Medien
    Digitale Medien
    Development of an advanced "volume'' H− source for neutral beam application (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 2378-2382 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Based on recent experimental results made on the large and small multicusp volume H− sources, a new multicusp source has been designed to generate high-brightness H− or D− beams for high duty factor or dc operations. Cesium will be introduced into the source plasma to enhance the H− output current. Arrangements for reducing the electrons as well as capturing them in the preaccelerator electrodes will be incorporated into the new source geometry.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1141367
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  • 8
    Digitale Medien
    Digitale Medien
    Postural dynamics in the standing human (1990)
    Springer
    Biological cybernetics 62 (1990), S. 309-320 
    Details
    ISSN: 1432-0770
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Informatik , Physik
    Notizen: Abstract The purpose of this study was to develop a mathematical model of the linkage dynamics in up-right standing, and to use this model to study output principles for postural control. The standing human was modelled in the sagittal plane as a three-segment linkage. Mechanical disturbances were simulated as forces which could be applied at various points in this linkage. An iterative approach was used to find joint torque combinations which would restore balance within 80ms of these mechanical disturbances. The model predicted that a specific proportional relationship was necessary between the hip, knee and ankle torques in order for balance to be restored. This proportional relationship was shown to be a function of the model structure, but independent of the location, direction and amplitude of the disturbance. These predictions were tested experimentally. A disturbance apparatus was designed to apply an impulsive force to the subjects. The joint torque responses of the subjects were in quantitative agreement with the predictions of the model. The results suggest that a fixed relationship between joint torques may be required to restore balance, and this fixed relationship may make the task of postural control simpler for the nervous system.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00201445
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  • 9
    Digitale Medien
    Digitale Medien
    Postural dynamics of walking in humans (1990)
    Springer
    Biological cybernetics 62 (1990), S. 321-330 
    Details
    ISSN: 1432-0770
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Informatik , Physik
    Notizen: Abstract The dynamics of postural control in human biped locomotion were studied using(1) a model, and(2) experimentally applied impulsive force disturbances. The model was planar, and contained five rigid segments, articulating at frictionless pin joints. The model was used to identify joint torque combinations which would successfully correct for an impulsive force disturbance applied at different points in the walking cycle. The simulation results suggested that(1) early responses (within 80ms) can be effective in compensating for impulsive disturbances,(2) the same strategies which successfully counteract similar disturbances during quiet standing are also effective in certain phases of the walking cycle,(3) modifications in the response strategies are needed to accomodate differences in the dynamics over the stride cycle, and(4) the swing leg is ineffective in compensating for disturbances in the short term. These model predictions were tested experimentally. Subject responses to an impulsive force disturbance applied during walking were studied. The electromyographic results generally support the model predictions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00201446
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  • 10
    Digitale Medien
    Digitale Medien
    Peak accelerations of the head experienced in boxing (1975)
    Springer
    Medical & biological engineering & computing 13 (1975), S. 396-404 
    Details
    ISSN: 1741-0444
    Schlagwort(e): Head accelerations in boxing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Beschreibung / Inhaltsverzeichnis: Sommaire On a déterminé la réaction du système tête-cou à une force extérieure en forçant le torse d'un sujet à se mouvoir d'avant en arrière, selon un tracé sinusoïdal, à diverses fréquences. La durée d'une impulsion de force caractéristique, telle que rencontrée dans la boxe, a été mesurée, et, de là, on a déduit que la tête est commandée par la masse, c'est-à-dire que l'effet de la rigidité et de l'amortissement du cou est négligeable. L'amplitude des impulsions de force a été mesurée au niveau inférieur de leur gamme dans une expérience effectuée simultanément sur une tête humaine et un modèle dynamiquement équivalent, et évaluée par extrapolation pour des niveaux plus élevés pour la tête. La durée et l'amplitude des impulsions évaluées ont été utilisées conjointement avec l'indice de gravité de Gaad—mis au point pour la sécurité routière—et on a constaté que dans une situation de boxe correspondant à la réalité, un ‘niveau de sécurité’ peut être dépassé par un facteur de quatre.
    Kurzfassung: Zusammenfassung Die Reaktion von Kopf und Nacken auf eine von außen angewandte Kraft wurde festgestellt, indem der Torso eines Objektes zur Bewegung nach vorne und hinten bei verschiedenen Frequenzen in sinusförmiger Weise gezwungen wurde. Die Dauer einer typischen Kraftperiode, wie man sie beim Boxen antrifft, wurde gemessen. Es wurde daraus gefolgert, daß der Kopf in dieser Situation durch die Masse gesteuert wird, d.h. die Steifigkeit und Dämpfwirkung des Nackens vernachlässigbar ist. Die Stärke der Kraftperioden wurde im unteren Bereich während eines gleichzeitig stattfindenden Experiments mit einem menschlichen Kopf und einer dynamisch gleichwertigen Attrappe durchgeführt und beim Kopf durch Extrapolation für den höheren Bereich geschätzt. Dauer und Stärke der geschätzten Perioden wurden in Verbindung mit dem Stärkeindex von Gadd geschätzt—der für die Verkehrssicherheit entwickelt wurde—und es wurde festgestellt, daß die ‘sichere Grenze’ beim eigentlichen Boxen um das 4-fache überstiegen werden kann.
    Notizen: Abstract By forcing the torso of a subject to move in a fore and aft direction, in a sinusoidal manner at various frequencies, the response of the head-neck system to an external force has been established. The duration of a typical pulse of force, as encountered in boxing, was measured, and hence it was inferred that in this situation the head is mass-controlled; i.e. the effect of the rigidity and damping of the neck is negligible. The magnitude of the force pulses has been measured at the lower level of their range in a concurrent experiment on a human head and a dynamically equivalent dummy, and by extrapolation estimated for higher levels for the head. The duration and magnitude of the estimated pulse were used in conjunction with the Gadd Severity Index—developed for road safety—and it was found that in a realistic boxing situation a ‘safe level’ can be exceeded by a factor of 4.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02477111
    Standort Signatur Erwartet Verfügbarkeit
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