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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.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Multiwire thermocouples: Frequency response

Experimental measurements are made with a novel two wire thermocouple. Signals from two wires of unequal diameters are recorded from the thermocouple suspended in constant flow with a periodic temperature fluctuation. It is demonstrated that the reconstructed signal from the two wire thermocouple requires no compensation for omega less than or equal to 2 omega(sub 1) where omega is the natural frequency of the smaller wire. A compensation factor is recommended for larger frequencies omega greater than 2 omega(sub 1). Theory and experimental measurements are compared with a novel three wire thermocouple. Signals from three wires of unequal diameters are recorded from the thermocouple suspended in constant flow with a periodic temperature fluctuation. It is demonstrated that the reconstructed signal from the three wire thermocouple requires no compensation for omega less than or equal to 5 omega(sub 1) where omega (sub 1) is the natural frequency of the smaller wire. The latter result represents a significant improvement compared to previous work with two wire thermocouples. A correction factor has also been derived to account for wires of arbitrary diameter. Measurements are recorded for multiwire thermocouples consisting of either two or three wires of unequal diameters. Signals from the multiwire probe are recorded for a reversing gas flow with a periodic temperature fluctuation. It is demonstrated that the reconstructed signal from the multiwire thermocouple requires no compensation provided omega/omega(sub 1) is less than 2.3 for two wires or omega/omega(sub 1) is less than 3.6 for three wires where omega(sub 1) is the natural frequency of the smaller wire based on the maximum gas velocity. The latter results were possible provided Fourier transformed data were used and knowledge of the gas velocity is available.

Forney, L. J.↗
NASA NTRS1995

Multiwire Thermocouples in Reversing Flow

Measurements are recorded for multiwire thermocouples consisting of either two or three wires of unequal diameters. Signals from the multiwire probe are recorded for a reversing gas flow with both a periodic temperature and time constant fluctuation. It is demonstrated that the reconstructed signal from the multiwire thermocouple requires no compensation provided omega/omega(sub 1) less than 2.3 for two wires or omega/omega(sub 1) less than 3.6 for three wires where omega(sub 1) (= 2(pi)f) is the natural frequency of the smaller wire based on the maximum gas velocity. The latter results were possible provided Fourier transformed data from the wires were used and knowledge of the gas velocity phase angle was available.

Forney, L. J.↗
NASA NTRS1972

Multiwire proportional counter development

A test run was made at the Bevatron to check the character of signals induced in an electromagnetic delay line capacitively coupled to the wire cathode plane of a multiwire proportional chamber. In particular, these signals and the behavior of the readout electronics as a function of associated delta-ray production are studied. These measurements are important in assessing the effect of delta-ray background on the spatial resolution attainable for the primary ions. Test results are used to design a multiwire proportional chamber and readout system for use as spatial detectors in a superconducting magnetic spectrometer experiment.

Source record↗
NASA NTRS1974

Secondary electron background produced by heavy nuclei in a multiwire proportional counter hodoscope

The secondary electron background produced by heavy nuclei in a multiwire proportional counter hodoscope is calculated using both a simplified and a more complete Monte Carlo model. These results are compared with experimental data from a small multiwire proportional counter hodoscope operated in a 530 MeV/nucleon accelerator beam of nitrogen nuclei. Estimates of the secondary electron background produced by heavy relativistic nuclei are presented along with the detailed results from calculations of energy deposition in the hodoscope counter cells.

Morgan, S. H., Jr.↗
NASA NTRS1985

Multiwire Gamma Camera for Radionuclide and Radiographic Imaging in the Space environment

Unique multiwire proportional counter technology has been developed at the Johnson Space Center over the past several years. The technology will be described and how it may apply both in near- and long-term NASA efforts. In the near-term, I feel that the technology will provide a significant tool for the cardiovascular research area. In particular, low-dose nuclear medicine and tissue densitometry techniques of expanded scope will be supplied. In the longer term, the multiwire technique can provide a general purpose radiology and nuclear medicine facility for use in the space station which would be difficult and costly to provide by other means.

Lacy, Jeffrey L.↗
NASA NTRS1973

Multiwire proportional chamber development

The development of large area multiwire proportional chambers, to be used as high resolution spatial detectors in cosmic ray experiments is described. A readout system was developed which uses a directly coupled, lumped element delay-line whose characteristics are independent of the MWPC design. A complete analysis of the delay-line and the readout electronic system shows that a spatial resolution of about 0.1 mm can be reached with the MWPC operating in the strictly proportional region. This was confirmed by measurements with a small MWPC and Fe-55 X-rays. A simplified analysis was carried out to estimate the theoretical limit of spatial resolution due to delta-rays, spread of the discharge along the anode wire, and inclined trajectories. To calculate the gas gain of MWPC's of different geometrical configurations a method was developed which is based on the knowledge of the first Townsend coefficient of the chamber gas.

Doolittle, R. F.↗
NASA NTRS1973

Measurements of the performance of multiwire proportional chambers

Data are presented that may be useful in formulating engineering specifications and test procedures for the proportional counter hodoscope to be flown as part of the High Energy Cosmic Ray Experiment on the High Energy Astronomy Observatory (HEAO), Mission A. A collection of preliminary data taken in laboratory tests of multiwire counters with an anode wire spacing of 5 mm and cathode gap spacing of 1 cm is presented. The data are from laboratory development models or counters for balloon flights and were selected to illustrate several aspects of proper and improper counter performance. Most of the data were taken from a large proportional counter hodoscope which has an active area of 0.5 by 0.5 m and 104 wires per plane.

Austin, R. W.↗
NASA NTRS1974

Results obtained with position sensitive multiwire proportional chambers with helium, carbon, and oxygen nuclei

Spatial resolution performance results obtained at the Lawrence Radiation Laboratory Bevatron with prototype multiwire proportional chamber spatial detectors with integral delay line readout are presented. The effects due to incident nuclei charge, chamber operating parameters, chamber design, electronics, gas mixtures, and magnetic field presence have been investigated and are discussed.

Emming, J. G.↗
NASA NTRS1974

A multiwire proportional counter system for high energy astrophysics

Resolution tests of multiwire proportional counter delay line readout systems are reported. The system is being developed at NASA/JSC for use in a large balloon borne magnet spectrometer. The system is ultimately intended for use in Space Shuttle missions. Tests of two different types of delay line and associated electronics carried out in minimum ionizing particle beams (accelerator and sea level cosmic ray) are reported. Resolution performance is shown to be strongly dependent on type of gas mixture and in the case of inclined events upon the propagation velocity of the delay line. The resolution performance achieved for magic gas chamber filling (100 um at normal incidence) is far superior to any other state of the art technique capable of being applied to large geometry factor systems.

Lacy, J. L.↗
NASA NTRS1975

An efficient read-out system for multiwire proportional counter hodoscopes

An efficient scanning method for read-out of a multiwire proportional counter hodoscope is presented. This method which utilizes the grouping of wires in the hodoscope read-out system offers distinct advantages in speed and simplicity over systems employing long shift registers. Power consumption and cost can be minimized with this method because of slower clock speeds and a low parts count. This system has been constructed and used on a hodoscope for cosmic-ray trajectory measurements and a lower-power version has been designed for satellite applications.

Austin, R. W.↗
NASA NTRS1977

Sensing circuits for multiwire proportional chambers

Integrated sensing circuits were designed, fabricated, and packaged for use in determining the direction and fluence of ionizing radiation passing through a multiwire proportional chamber. CMOS on sapphire was selected because of its high speed and low power capabilities. The design of the proposed circuits is described and the results of computer simulations are presented. The fabrication processes for the CMOS on sapphire sensing circuits and hybrid substrates are outlined. Several design options are described and the cost implications of each discussed. To be most effective, each chip should handle not more than 32 inputs, and should be mounted on its own hybrid substrate.

Peterson, H. T.↗
NASA NTRS1978

The application of a drift multiwire proportional counter to the imaging of low energy X-rays

A 75 mm x 75 mm multiwire proportional counter (MWPC) with a 1 micron polypropylene window has been built to map low energy X-rays. The MWPC is constructed with a large drift region which allows us to use the center-of-gravity technique to improve the counter's efficiency and position resolution. Using 330 torr of propane as the gas fill and an anode plane composed of 20 micron diameter Au-plated tungsten wire spaced 1 mm apart, a position resolution of better than 240 microns (FWHM) in two orthogonal directions at an X-ray energy of 0.94 keV has been achieved.

Ku, W. H.-M.↗
NASA NTRS1979

A drift multiwire proportional counter for cosmic soft X-ray imaging

Multiwire proportional counters with 1 micrometer polypropylene windows, of dimensions 75 mm x 75 mm and 100 mm x 100 mm, have been built to map soft cosmic X-rays. The counters are constructed with a large drift region which makes it possible to use the center-of-gravity technique to improve the counter's efficiency and position resolution. Using 330 torr of propane as the gas fill and an anode plane composed of 20 micrometer diameter, gold-plated tungsten wire spaced 1mm apart, a position resolution of better than 280 micrometers (FWHM) in two orthogonal directions at an X-ray energy of 0.94 keV was achieved.

Reid, P. B.↗
NASA NTRS1991

High speed multiwire photon camera

An improved multiwire proportional counter camera having particular utility in the field of clinical nuclear medicine imaging. The detector utilizes direct coupled, low impedance, high speed delay lines, the segments of which are capacitor-inductor networks. A pile-up rejection test is provided to reject confused events otherwise caused by multiple ionization events occuring during the readout window.

Lacy, Jeffrey L.↗
NASA NTRS1989

High speed multiwire photon camera

An improved multiwire proportional counter camera having particular utility in the field of clinical nuclear medicine imaging. The detector utilizes direct coupled, low impedance, high speed delay lines, the segments of which are capacitor-inductor networks. A pile-up rejection test is provided to reject confused events otherwise caused by multiple ionization events occurring during the readout window.

Lacy, Jeffrey L.↗
NASA NTRS1972

A low power X-ray diffractometer for soil analysis in remote locations employing a multiwire proportional counter detector array.

A low power X-ray powder diffraction system suitable for remote mineralogical analysis of lunar, planetary, or asteroid soils has been designed. A one Curie Fe-55 source provides a monochromatic X-ray beam of 5.9 keV. Seeman-Bohlin focusing geometry is employed in the camera, allowing peak detection to proceed simultaneously at all angles and obviating the need for moving parts. The detector system is an array of 500-600 proportional counters with a wire-spacing of 1 mm. An electronics unit comprising preamplifier, postamplifier, window discriminators, and storage flip-flops requiring only 3.5 milliwatts has been designed and tested. Total instrument power is less than 5 W.

Gregory, J. C.↗
NASA NTRS1977

Skin-implant multiwire connector

Construction of device utilizing high-purity carbon is biocompatible as well as hygienic, Design allows for easy connections and disconnections in dark, cleaning and maintenance and less snagging of clothing and other articles by device. Guides and magnetic coupling preclude need for locks, screwing, or latching.

Owens, L. J.↗