Performance of a ten-stage electrostatic depressed collector for klystrons
Klystron power conversion efficiency augmentation by electrostatic depressed collector design, presenting performance prediction calculation method
Mihran, T. G.↗
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High efficiency collector for microwave tubes
Depressed collector has basic configuration of a dish with a central cone and protruding spike. This geometry velocity sorts and slows the electrons down to minimum velocity at collection, and prevents backstreaming of secondaries and reflected primaries into interaction region of the tube.
Kosmahl, H. C.↗
Numerical method and FORTRAN program for the solution of an axisymmetric electrostatic collector design problem
The numerical calculation is described of the steady-state flow of electrons in an axisymmetric, spherical, electrostatic collector for a range of boundary conditions. The trajectory equations of motion are solved alternately with Poisson's equation for the potential field until convergence is achieved. A direct (noniterative) numerical technique is used to obtain the solution to Poisson's equation. Space charge effects are included for initial current densities as large as 100 A/sq cm. Ways of dealing successfully with the difficulties associated with these high densities are discussed. A description of the mathematical model, a discussion of numerical techniques, results from two typical runs, and the FORTRAN computer program are included.
Reese, O. W.↗
Comparative performance of twenty-three types of flat plate solar energy collectors
Report compares efficiencies of 23 solar collectors for four different purposes: operating a Rankine-cycle engine, heating or absorption air conditioning, heating hot water, and heating a swimming pool.
Simon, F. F.↗
Effect of grid transparency and finite collector size on determining ion temperature and density by the retarding potential analyzer
The effects of the grid transparency and finite collector size on the values of thermal ion density and temperature determined by the standard RPA (retarding potential analyzer) analysis method are investigated. The current-voltage curves calculated for varying RPA parameters and a given ion mass, temperature, and density are analyzed by the standard RPA method. It is found that only small errors in temperature and density are introduced for an RPA with typical dimensions, and that even when the density error is substantial for nontypical dimensions, the temperature error remains minimum.
Troy, B. E., Jr.↗
Horizontally-mounted solar collector
System consists of three major components: vertical deflector assembly, stationary reflector, and motor driven tracking mechanism. Deflector assembly directs incident incoming energy to a vertical direction, using series of horizontally mounted vanes. Energy is then redirected via reflector to fixed collector.
Black, D. H.↗
Performance of a solar-thermal collector
Possible means of achieving the technology required for field application of solar thermal power systems are discussed. Simplifications in construction techniques as well as in measurement techniques for parabolic trough collectors are described. Actual measurement data is also given.
Higa, W. H.↗
High performance flat plate solar collector
The potential use of porous construction is presented to achieve efficient heat removal from a power producing solid and is applied to solar air heaters. Analytical solutions are given for the temperature distribution within a gas-cooled porous flat plate having its surface exposed to the sun's energy. The extracted thermal energy is calculated for two different types of plate transparency. Results show the great improvement in performance obtained with porous flat plate collectors as compared with analogous nonporous types.
Lansing, F. L.↗
Fabrication of a focusing soft X-ray collector payload
A large area X-ray focusing collector with arc minute resolution and a position sensitive detector capable of operating in the soft X-ray region was developed for use on sounding rockets in studying stellar X-ray sources. The focusing payload consists of the following components, which are described: (1) a crossed paraboloid mirror assembly; (2) an aspect camera and star tracker; (3) a focal plane assembly containing an imaging proportional counter and its preamplifiers, high voltage power supplies and gas system; (4) a fiducial system; and (5) housekeeping, data handling, instrumentation and telemetry electronics. The design, tests, and operation are described.
Davis, J. M.↗
Steady-state heat transfer in transversely heated porous media with application to focused solar energy collectors
A fluid flowing in a porous medium heated transversely to the fluid flow is considered. This configuration is applicable to a focused solar energy collector for use in an electric power generating system. A fluidized bed can be regarded as a porous medium with special properties. The solutions presented are valid for describing the effectiveness of such a fluidized bed for collecting concentrated solar energy to heat the working fluid of a heat engine. Results indicate the advantage of high thermal conductivity in the transverse direction and high operating temperature of the porous medium.
Nichols, L. D.↗
Collectors for vacuum-cleaning lines
See-through vacuum cleaning collector devices ease retrieval of small lost parts.
Hinze, W. L.↗
Inexpensive high-temperature solar collector
Similar to flat-plate collector, concentrator uses water lenses to achieve temperatures near 200 degrees Centigrade. Lens assembly consists of parallel cylindrical lenses made of glass or plastic shells, reducing manufacturing costs and improving portability.
Dorman, J.↗
"Tubless" flat-plate solar collector
Solar collector utilizing spray system, effectively removes heat from absorber plates without use of tubing or channeling.
Zeldin, B.↗
An 82 to 84 percent efficient, small size, 2 and 4 stage depressed collector for octave bandwidth high performance TWT's
Improvements were carried out on a TWT (traveling wave tube) for use in EMC (electronic countermeasure) systems by applying MDC (multi-stage depressed collector) and spent-beam refocusing techniques. The MDC geometric design consists of six collecting elements (electrodes) at ground and cathode potentials operating in 2 or 4 stage configuration. The refocusing system designed allows a controlled beam expansion to the point that space charge becomes negligible at the MDC entrance. Simultaneously, the standard deviation of the radial velocity (angular spread) is reduced. This system provides an analog real time readout of P(recovered). Data on all tests is obtained with an automated data acquisition system.
Kosmahl, H.↗
Processing on high efficiency solar collector coatings
Wavelength selective coatings for solar collectors are considered. Substrates with good infrared reflectivity were examined along with their susceptibility to physical and environmental damage. Improvements of reflective surfaces were accomplished through buffing, chemical polishing and other surface processing methods.
Roberts, M.↗
Analysis of spent beam refocusing to achieve optimum collector efficiency
A reasonable criterion for evaluating the effectiveness of spent beam refocusing is the reduction of spent beam turbulence. The rms deviation of particle angles where the angles are calculated from the ratio of radial velocity to axial velocity is one measure of beam turbulence. It is demonstrated that the angular deviation can be reduced by almost half in some magnetic field configurations. Experimental evidence indicates that beam processing of this type is most likely to yield an optimum collector efficiency.
Stankiewicz, N.↗
Small-size 81- to 83.5-percent efficient 2- and 4-stage depressed collectors for octave-bandwidth high-performance TWT's
In a joint USAF-NASA Program, Lewis Research Center is carrying out an efficiency improvement program on traveling wave tubes for use in electronic counter measures by applying multistage depressed collector (MDC) and spent beam refocusing techniques. In the analytic part of the effort, three-dimensional electron trajectories are computed throughout the TWT. On the experimental side, tube performance is evaluated first without the MDC; then, the spent beam is analyzed for symmetry, circularity, and velocity spread. The three-dimensional theory predicts a MDC-efficiency, at mid-band, of 81 per cent for a 2-stage MDC with symmetric, circular, and optimally refocused beams and 85.5 per cent for a 4-stage MDC. Experimental results to date have yielded MDC efficiencies of a minimum of 81 and 83 per cent for a 2- and 4-stage MDC, respectively, across a one-octave bandwidth of a 4.8 to 9.6 GHz 330-to-550-W TWT.
Kosmahl, H. G.↗
Testing of three hot- air solar collectors
Report presents procedures used and results obtained during program to determine pressure drops across three prototype hot-air solar collectors as function of air velocity and operating temperature.
Losey, R.↗