Thermal pump-compressor for space use Patent

Thermal pump-compressor for converting solar energ

Feasibility of standard evaluation procedures for ablating materials

Teflon and high density phenolic-nylon models evaluated at various enthalpies and heating rates under supersonic condition

Pulsed electromagnetic gas acceleration

Terminal voltage measurements with long cathodes in a high power, quasi-steady MPD discharge show that the critical current for the onset of voltage fluctuations, which was previously shown to be a function of cathode area, approaches an asymptote for cathodes of very large surface area. Floating potential measurements and photographs of the discharge luminosity indicate that the fluctuations are confined to the vicinity of the cathode and hence reflect a cathode emission process rather than a fundamental limit on MPD performance. Photoelectric measurements of particular argon neutral and ion transitions show that the higher electronic states are populated more heavily than would be calculated on the basis of Saha-Boltzmann equilibrium at the local electron temperature and number density. Preliminary optical depth measurements show that for a current of 4 kA and an argon mass flow of 12 g/sec, a population inversion exists between the upper and lower states of the 4880 A argon ion transition

Pulsed electromagnetic gas acceleration

Detailed measurements of the axial velocity profile and electromagnetic structure of a high power, quasi-steady MPD discharge are used to formulate a gasdynamic model of the acceleration process. Conceptually dividing the accelerated plasma into an inner flow and an outer flow, it is found that more than two-thirds of the total power in the plasma is deposited in the inner flow, accelerating it to an exhaust velocity of 12.5 km/sec. The outer flow, which is accelerated to a velocity of only 6.2 km/sec, appears to provide a current conduction path between the inner flow and the anode. Related cathode studies have shown that the critical current for the onset of terminal voltage fluctuations, which was recently shown to be a function of the cathode area, appears to reach an asymptote for cathodes of very large surface area. Detailed floating potential measurements show that the fluctuations are confined to the vicinity of the cathode and hence reflect a cathode emission process rather than a fundamental limit on MPD performance

Pulsed electromagnetic gas acceleration

Experimental data were combined with one-dimensional conservation relations to yield information on the energy deposition ratio in a parallel-plate accelerator, where the downstream flow was confined to a constant area channel. Approximately 70% of the total input power was detected in the exhaust flow, of which only about 20% appeared as directed kinetic energy, thus implying that a downstream expansion to convert chamber enthalpy into kinetic energy must be an important aspect of conventional high power MPD arcs. Spectroscopic experiments on a quasi-steady MPD argon accelerator verified the presence of A(III) and the absence of A(I), and indicated an azimuthal structure in the jet related to the mass injection locations. Measurements of pressure in the arc chamber and impact pressure in the exhaust jet using a piezocrystal backed by a Plexiglas rod were in good agreement with the electromagnetic thrust model

Pulsed electromagnetic gas acceleration

Terminal voltage measurements with various cathodes and anodes in a high power, quasi-steady magnetoplasmadynamic (MPD) are discussed. The magnitude of the current at the onset of voltage fluctuations is shown to be an increasing function of cathode area and a weaker decreasing function of anode area. Tests with a fluted cathode indicated that the fluctuations originate in the plasma adjacent to the cathode rather than at the cathode surface. Measurements of radiative output from an optical cavity aligned to examine the current-carrying portion of a two-dimensional, 56 kA magnetoplasmadynamic discharge reveal no lasing in that region, consistent with calculations of electron excitation and resonance radiation trapping. A voltage-swept double probe technique allows single-shot determination of electron temperature and electron number density in the recombining MPD exhaust flow. Current distributions within the cavity of MPD hollow cathodes for various static prefills with no injected mass flow are examined

Inventory of wetlands and agricultural land cover in the upper Sevier River Basin, Utah

The use of color infrared aerial photography in the mapping of agricultural land use and wetlands in the Sevier River Basin of south central utah is described. The efficiency and cost effectiveness of utilizing LANDSAT multispectral scanner digital data to augment photographic interpretations are discussed. Transparent overlays for 27 quadrangles showing delineations of wetlands and agricultural land cover were produced. A table summarizing the acreage represented by each class on each quadrangle overlay is provided

Irrigated acreage in the Bear River Basin as of the 1975 growing season

The irrigated cropland in the Bear River Basin as of the 1975 growing season was inventoried from satellite imagery. LANDSAT color infrared images (scale 1:125,000) were examined for early, mid, and late summer dates, and acreage was estimated by use of township/section overlays. The total basin acreage was estimated to be 573,435 acres, with individual state totals as follows: Idaho 234,370 acres; Utah 265,505 acres; and Wyoming 73,560 acres. As anticipated, wetland areas intermingled among cropland appears to have produced an over-estimation of irrigated acreage. According to a 2% random sample of test sites evaluated by personnel from the Soil Conservation Service such basin-wide over-estimation is 7.5%; individual counties deviate significantly from the basin-wide figure, depending on the relative amount of wetland areas intermingled with cropland

Pulsed electromagnetic gas acceleration Semiannual progress report, 1 Jul. - 31 Dec. 1969

Exhaust velocities of arc plasma flow in pulsed electromagnetic gas accelerato

Joint demodulation of low-entropy narrowband cochannel signals

Introducation to cochannel signals: many receivers today operate in an interference-limited environment. In a dense signal environment, the performance of a receiver is limited by interference from multiple signals at the receiver rather than signal-to-noise ratio. In the interference-limited environment, there is a diminishing return from investing additional resources into improving traditional receiver parameters such as noise figure. Advanced processing techniques exist that can help recover information that would otherwise be lost using a single-channel receiver. This work investigates some of these techniques. Interference may originate from many sources, such as users on the same or adjacent frequency band, unintended emissions, and intermodulation. This work investigates interference from cochannel information bearing signals. Cochannel interference is commonly defined as the reception of two or more signals at the receiver overlapping in frequency and in time.USA