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At least 109 records · Page 6

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NASA NTRS1974

Characteristics and performance of several mass spectrometer residual gas analyzers

The operation and properties of various mass-spectrometer residual gas analyzers for use in vacuum measurements were analyzed in terms of efficiencies of ion extraction, ion separation and transmission, and ion collection. Types of instruments studied were magnetic sector, omegatron, quadrupole, and monopole. Experimental results presented include absolute sensitivity to argon, relative sensitivity to 10 gases, and cracking patterns for these gases. It is shown that the properties are strongly dependent on instrument range, resolution, and the particular voltages, currents, or field intensities used to control the instrument.

Hultzman, W. W.↗

NASA NTRS1974

Collecting efficiency of a cylindrical mirror electron energy analyzer with preretarding lens

The electron collecting efficiency of a cylindrical mirror energy analyzer incorporating retardation of the electrons prior to analysis has been determined over the range 0 to 30 eV by two methods. The first method requires the use of a vacuum ultraviolet monochromator to produce monoenergetic electrons of different energies; the second method involves measuring the energy-brightness relationship of the retarding optics and should be applicable to any deflection analyzer with pre-retarding optics. The results of the two methods are compared and the limitations of the latter method are discussed.

Gardner, J. L.↗

NASA NTRS1975

Portable automatic blood analyzer

Analyzer employs chemical-sensing electrodes for determination of blood, gas, and ion concentrations. It is rugged, easily serviced, and comparatively simple to operate. System can analyze up to eight parameters and can be modified to measure other blood constituents including nonionic species, such as urea, glucose, and oxygen.

Coleman, R. L.↗

NASA NTRS1974

Results from computer program for analyzing scattered light suppression systems for large space telescope

A computer program was developed which has the ability to analyze the performance of most light suppression systems so as to predict the amount of scattered light which will reach the image plane for various conditions of unwanted light input from the sun, earth, or moon. This program was used to analyze three different configurations of the large space telescope (LST): an LST with a truncated sunshield, an LST with an extended cylindrical sunshield, and an LST with a conical sunshield which is tilted upwards. The computer program gives the user detailed information as to the paths taken by the unwanted stray light to reach the image plane, and pinpoints those portions of the light suppression system which contribute most of the stray light, so that areas requiring improvements are evident. Certain design guide lines were formulated for any light suppression system selected for the LST, and one which meets these requirements (the tilted sunshade) is described in detail.

Tifft, W. G.↗

NASA NTRS1974

Application of a numerical differencing analyzer computer program to a Modular Integrated Utility System

This paper describes the application of a numerical differencing analyzer computer program to the thermal analyzation of a MIUS model. The MIUS model which was evaluated is one which would be required to support a 648-unit Garden Apartment Complex. This computer program was capable of predicting the thermal performance of this MIUS from the impressed electrical, heating, and cooling loads.

Brandli, A. E.↗

NASA NTRS1975

Collecting efficiency of a cylindrical mirror electron energy analyzer with pre-retarding lens

Gardner, J. L.↗

NASA NTRS1975

Interpretation of neutral particle analyzer measurements on plasmas having azimuthal drift

The theoretical model accounts for drift and cyclotron components of ion motion in a partially ionized plasma. Density and velocity distributions are systematically prescribed. The flux into the neutral particle analyzer (NPA) from this plasma is determined by summing over all charge exchange neutrals in phase space which are directed into apertures. Calculation of the process is continued through the NPA using appropriate cross section data to obtain analyzer output distributions. Theoretical results were compared with NPA measurements on four plasma heating devices having radial electric, E, and axial magnetic, B, fields. Drift velocity, in the azimuthal direction is identified with E/B. Selection of randomized cyclotron velocity distributions about mean azimuthal drift yield energy distributions which compare well with experiment.

Englert, G. W.↗

NASA NTRS1975

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.↗

NASA NTRS1975

Particulate size distribution cascade analyzer for spacecraft contamination monitoring

A cascade particulate analyzer was developed for nearly real time measurement of the contaminating particulate size distribution in the spacecraft interior ambient environment and as a real time total impacting particulate mass monitor under vacuum conditions. The analyzer has four stages, the first stage is a basic 10 MHz quartz crystal microbalance used widely on spacecraft (such as Skylab) for contamination monitoring purposes. In this application the front sensing crystal is coated with a low vapor pressure adhesive grease which captures impacting particles. This first stage has a wide viewing angle and measures total particulate mass impacting the crystal while the unit is exposed to the vacuum environment. The remaining three states form an aerodynamic impaction cascade with individual quartz crystal microbalances at each stage acting as accumulated mass sensing elements. These three stages thus give relative mass distribution of particulates in three ranges, particles having effective diameter greater than 5 micron, particles between 1 and 5 micron diameter and particles 0.3 to 1 micron diameter.

Wallace, D. A.↗

NASA NTRS1976

Finite element computer program to analyze cracked orthotropic sheets

A two dimensional orthotropic sheet with through-the-thickness cracks and temperature gradient was analyzed. The program includes special crack tip elements that account for singular stress fields associated with crack opening and crack sliding displacements at the crack tip. The program also includes a linear spring element and a constant strain, triangular element. A number of problems for which closed form solutions exist were analyzed to demonstrate the capabilities of the program.

Chu, C. S.↗

NASA NTRS1977

An investigation of accelerating mode and decelerating mode constant-momentum mass spectrometry and their application to a residual gas analyzer

A theoretical analysis of constant momentum mass spectrometry was made. A maximum resolving power for the decelerating mode constant momentum mass spectrometer was shown theoretically to exist for a beam of ions of known energy. A vacuum system and an electron beam ionization source was constructed. Supporting electronics for a residual gas analyzer were built. Experimental investigations of various types of accelerating and decelerating impulsive modes of a constant momentum mass spectrometer as applied to a residual gas analyzer were made. The data indicate that the resolving power for the decelerating mode is comparable to that of the accelerating mode.

Ng, Y. S.↗

NASA NTRS1977

Design and fabrication of a basic mass analyzer and vacuum system

A two-inch hyperbolic rod quadrupole mass analyzer with a mass range of 400 to 200 amu and a sensitivity exceeding 100 packs per billion has been developed and tested. This analyzer is the basic hardware portion of a microprocessor-controlled quadrupole mass spectrometer for a Gas Analysis and Detection System (GADS). The development and testing of the hyperbolic-rod quadrupole mass spectrometer and associated hardware are described in detail.

Judson, C. M.↗

NASA NTRS1977

Plasma analyzer for the Pioneer Jupiter missions

A description is given of the NASA/Ames Research Center Plasma Probe on board the Jupiter Missions of the Pioneer 10 and 11 spacecraft. The instrument has two quadrispherical electrostatic analyzer units; one has high sensitivity and resolution and the other is capable of measuring large fluxes of solar wind particles. The two analyzer units measure particle energy-to-charge ratio, flux, and direction of flow for positive ions and electrons over the wide range of particle densities found in the solar wind during the Jupiter missions. Data formats in space and ground data processing, the NASA/Ames Research Center plasma probe calibration facility, and the instrument response functions are also described.

Mckibbin, D. D.↗

NASA NTRS1979

Wideband digital spectrum analyzer

Modular spectrum analyzer consisting of RF receiver, fast fourier transform spectrum analyzer, and data processor samples stochastic signals in 220 channels. Construction reduces design and fabrication costs of assembled unit.

Morris, G. A., Jr.↗

NASA NTRS1978

JPL 2-to-the-20th-power channel 300 MHz bandwidth digital spectrum analyzer

A million (two to the 20th power) channel, 300 MHz bandwidth, digital spectrum analyzer was considered. The design, fabrication, and maintenance philosophy of the modular, pipelined, fast fourier transform (FFT) hardware are described. The spectrum analyzer will be used to examine the region from 1.4 GHz to 26 GHz for radio frequency interference which may be harmful to present and future tracking missions of the Deep Space Network. The design has application to the search for extraterrestrial intelligence signals and radio science phenomena.

Morris, G. A., Jr.↗

NASA NTRS1979

A rocket-borne electrostatic analyzer for measurement of energetic particle flux

A rocket-borne electrostatic analyzer experiment is described. It is used to measure energetic particle flux (0.9 to 14 keV) in the nighttime midlatitude E region. Energetic particle precipitation is believed to be a significant nighttime ionization source, particularly during times of high geomagnetic activity. The experiment was designed for use in the payload of a Nike Apache sounding rocket. The electrostatic analyzer employs two cylindrical parallel plates subtending a central angle of 90 deg. The voltage waveform supplied to the plates is a series of steps synchronized to the spin of the payload during flight. Both positive and negative voltages are provided, extending the detection capabilities of the instrument to both electrons and protons (and positive ions). The development, construction and operation of the instrument is described together with a preliminary evaluation of its performance in a rocket flight.

Pozzi, M. A.↗

NASA NTRS1981

Simplified thermal analyzer

Simplified Shuttle Payload Thermal Analyzer (SSPTA) aids in evaluating thermal design of instruments to be flown in Space Shuttle cargo bay. It is collection of programs that are currently used in thermal analysis of spacecraft, modified for quick, preliminary analysis of payloads. Although designed primarily to analyze Shuttle payloads, it can be easily used for thermal analysis in other situations.

Coyle, M. J.↗

NASA NTRS1979

Computational methods for analyzing the transmission characteristics of a beta particle magnetic analysis system

Computational methods were developed to study the trajectories of beta particles (positrons) through a magnetic analysis system as a function of the spatial distribution of the radionuclides in the beta source, size and shape of the source collimator, and the strength of the analyzer magnetic field. On the basis of these methods, the particle flux, their energy spectrum, and source-to-target transit times have been calculated for Na-22 positrons as a function of the analyzer magnetic field and the size and location of the target. These data are in studies requiring parallel beams of positrons of uniform energy such as measurement of the moisture distribution in composite materials. Computer programs for obtaining various trajectories are included.

Singh, J. J.↗