1,080 research outputs found
Diagnostics of effusing plasmas
A no. of diagnostics to measure all plasma properties in the vicinity of the hollow cathode are described. The momentum balance in the plasma and the source properties of the hollow cathode are detd. The main driving term in the momentum balance is the pressure gradient of ions and electrons. The deceleration of the ions is mainly caused by ion viscosity and to some extent by friction with neutrals. At high currents the ion flux almost equals the gas flux. At high gas flows the ion flux sats. [on SciFinder (R)
Plasma flow in an argon cascade arc
A model is described for the plasma flow in an Ar cascade arc which takes into account the heating and pressure effects. As the pressure increases the elec. field increases and the arc temp. decreases. The results agree with exptl. detns. [on SciFinder (R)
Experiments on the longitudinal ion momentum balance in a magnetized plasma
In the magnetized plasma of a hollow cathode arc the longitudinal and rotational drift velocities of ions have been measured, together with the electron and neutral densities and the temperatures of ions, electrons, and neutrals. The radial and longitudinal gradients of these quantities have been established. The ions drift against the electric field towards the anode with velocities between about 500 and 2500 m/s, driven by the plasma pressure gradient which is balanced by viscous deceleration and by friction against the surrounding neutral gas. The classical theory of the momentum balance with a turbulent contribution to the viscosity provides a good description of the longitudinal ion transport and explains direction and magnitude of the occurring drift velocity
Collective CO2 laser scattering on moving discharge structures in the submillimeter range in a magnetohydrodynamic generator
Collective scattering of CO/sub 2/ laser light on electrons is used to determine the radial scale length of the discharge structures occurring in a closed cycle magnetohydrodynamic generator. Heterodyne detection of scattered radiation is used to obtain a spatial resolution in the submillimeter range and to increase the signal to noise ratio. A discharge model is formulated to interpret the measured signals. The scale length of the electron density fluctuations is found to be (2.5+or-0.5)*10/sup -4/
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Analysis of gaseous-phase stable and radioactive isotopes in the unsaturated zone, Yucca Mountain, Nevada
The Nevada Nuclear Waste Storage Investigations Project of the US Department of Energy provides that agency with data for evaluating volcanic tuff beneath Yucca Mountain, Nevada, to determine its suitability for a potential repository of high-level radioactive waste. Thickness of the unsaturated zone, which consists of fractured, welded and nonwelded tuff, is about 1640 to 2460 feet (500 to 750 meters). One question to be resolved is an estimate of minimum ground-water traveltime from the disturbed zone of the potentail repository to the accessible environment. Another issue is the potential for diffusive or convective gaseous transport of radionuclides from an underground facility in the unsaturated zone to the accessible environment. Gas samples were collected at intervals to a depth of 1200 feet from the unsaturated zone at Yucca Mountain, Nevada. Samples were analyzed for major atmospheric gases; carbon dioxide in the samples was analyzed for carbon-14 activity and for {delta}2!{sup 3}C; water vapor in the samples was analyzed for deuterium and oxygen-18. These data could provide insight into the nature of unsaturated zone transport processes. 15 refs., 4 figs., 4 tabs
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