SEARCH · Search NASA
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Intense, steady-state cathode-luminescence has been observed from exposure of quartz powder to a low pressure rf-excited argon plasma discharge. The emission spectra (400 to 850 nm) associated with the powder luminescence were documented as a function of bias voltage using a spectrometer. The emission was broad-band, essentially washing out the line spectra features of the argon plasma discharge.
A preliminary experiment was performed to investigate conversion of 10.6 micron laser energy to electrical energy via a laser-sustained argon plasma. Short-circuit currents of 0.7 A were measured between a thoriated-tungsten emitter and collector electrodes immersed in the laser-sustained argon plasma. Open-circuit voltages of about 1.5 V were inferred from the current-voltage load characteristics. The dominant mechanism of laser energy conversion is uncertain at this time. Much higher output powers appear possible.
Low density cesium seeded argon plasma source with graphite element heat exchanger
Argon plasma oscillations stimulated by high energy pre-bunched electron beam from linear accelerator
Thermal conditions in asymptotic region of atmospheric pressure Ar arc plasma, considering nonequilibrium ionization due to ambipolar diffusion
Analysis of convective laminar boundary layer structures in high density shock heated argon plasma flow
Stark broadening of spectral lines in argon plasma and need to include Debye shielding effects
Mixing and temperature measurements on argon plasma operating as heater for surrounding sheath of air or hydrogen
Experiments on a thermally ionized argon plasma suggest that applying a Lorentz force by means of orthogonal electric and magnetic fields to an electrically conducting fluid flow imposes necessary but not sufficient conditions for acceleration. There are, in fact, many combinations of current and magnetic field which cause decelerations of the fluid. The deceleration arises from a retarding force which may be larger than the applied Lorentz force. The retarding force causing the deceleration is a consequence of currents circulating completely within the fluid. These currents arise from differences in velocity between the central and wall regions of the duct which interact with the imposed magnetic field to produce differences in induced voltages. The observed physical effects of the circulating currents cause a loss in velocity in the central region of the duct, an increase in thermal energy in the sidewall region, and little change in thermal energy near the electrode wall region. For similar velocity profiles, the adverse effects appear to be related to the product of electrical conductivity and velocity, and performance as an accelerator appears to be controlled by the Hoffman loading parameter (i.e., the ratio of the applied to the induced currents).
Increased electrical conductivity of cesium-seeded argon plasma for magnetogasdynamic power source
Properties and phase diagrams of magnesium binary systems, thermal diffusion of refractory metals, plasma physics, sodium-potassium seeded argon plasma, and convection electrolysis transients
Cesium fluoride and argon plasma additive effects in thermionic converters
Magnetic field effect on flow field and drag of blunt body in partially ionized argon plasma, obtaining electron density and temperature
Elliptical patterns on emission lines of argon plasma jets attributed to antihalation backing during hypersensitization of film
Sodium-potassium seeded argon plasma in electric field measured for electrical conductivity
The axial flow and heating of an argon plasma in a pinched plasma column of a pulsed, linear z-pinch device was experimentally examined with a unique pressure sensing instrument capable of resolving mass flow properties. Transient axial pressure profiles identify periods of intense flow and heating. Mechanisms generating such effects are considered.
A microwave digestion procedure, followed by Inductively Coupled Argon Plasma Spectroscopy, is described for the determination of boron (B) in human plasma. The National Institute of Standards and Technology (NIST) currently does not certify the concentration of B in any substance. The NIST citrus leaves 1572 (CL) Standard Reference Material (SRM) and wheat flour 1567a (WF) were chosen to determine the efficacy of digestion. CL and WF values compare favorably to those obtained from an open-vessel, wet digestion followed by ICP, and by neutron activation and mass spectrometric measurements. Plasma samples were oxidized by doubled-distilled ultrapure HNO3 in 120 mL PFA Teflon vessels. An MDS-81D microwave digestion procedure allows for rapid and relatively precise determination of B in human plasma, while limiting handling hazards and sources of contamination.
Conductivity of potassium-seeded argon plasma, assuming variable collision cross sections and Maxwellian distribution for electrons