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  • 1
    Electronic Resource
    Electronic Resource
    Effects of eruption history and cooling rate on lava dome growth (1995)
    Springer
    Bulletin of volcanology 57 (1995), S. 229-239 
    Details
    ISSN: 1432-0819
    Keywords: Lava dome ; Lava flowmechanisms ; Laboratory simulations ; Mt St Helens ; Soufrière of St Vincent ; Venus volcanism ; Pancake domes ; Planetary volcanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract To better understand the factors controlling the shapes of lava domes, laboratory simulations, measurements from active and prehistoric flows and dimensional analysis were used to explore how effusion history and cooling rate affect the final geometry of a dome. Fifty experiments were conducted in which a fixed volume of polyethylene glycol wax was injected into a tank of cold sucrose solution, either as one continuous event or as a series of shorter pulses separated by repose periods. When the wax cooling rates exceeded a critical minimum value, the dome aspect ratios (height/diameter) increased steadily with erupted volume over the course of a single experiment and the rate at which height increased with volume depended linearly on the time-averaged effusion rate. Thus the average effusion rate could be estimated from observations of how the dome shape changed with time. Our experimental results and dimensional analyses were compared with several groups of natural lava flows: the recently emplaced Mount St Helens and Soufrière domes, which had been carefully monitored while active; three sets of prehistoric rhyolite domes that varied in eruptive style and shape; and two sets of Holocene domes with similar shapes, but different compositions. Geometric measurements suggest that dome morphology can be directly correlated with effusion rate for domes of similar composition from the same locality, and that shape alone can be related to a dimensionless number comparing effusion rate and cooling rate. Extrapolation to the venusian ‘pancake domes’ suggests that they formed from relatively viscous lavas extruded either episodically or at average effusion rates low enough to allow solidified surface crust to exert a dominating influence on the final morphology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00265423
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  • 2
    Electronic Resource
    Electronic Resource
    Design study of a 120-keV,3He neutral beam injector (1981)
    Springer
    Journal of fusion energy 1 (1981), S. 69-86 
    Details
    ISSN: 1572-9591
    Keywords: Neutral beam injector ; fusion ; 3He ; direct energy conversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract We describe a design for a 120-keV, 2.3-MW,3He neutral beam injector for use on a D-3He fusion reactor. The constraint that limits operating life when injecting He is its high sputtering rate. The sputtering is partly controlled by using an extra grid to prevent ion flow from the neutralizer duct to the electron suppressor grid, but a tradeoff between beam current and operating life is still required. Hollow grid wires functioning as mercury heat pipes cool the grid and enable steady state operation. Voltage holding and radiation effects on the acceleration grid structure are discussed. We also briefly describe the vacuum system and analyze use of a direct energy converter to recapture energy from unneutralized ions exiting the neutralizer. Of crucial importance to the technical feasibility of the3He-burning reactor are the injector efficiency and cost; these are 53% and $5.5 million, respectively, when power supplies are included.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01050450
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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