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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Neutral Composition Measurements by the Pioneer Venus Neutral Mass Spectrometer During Orbiter Re-Entry

Measurements by the Pioneer Venus Orbiter Neutral Mass Spectrometer (ONMS) instrument during Orbiter re-entry have been made from 18-24 hours local solar time, above 170 km, of He, and from midnight to 4.5 hours below 200 km of He, N, O, CO, N2, and CO2. Preliminary results indicate that in the post-midnight sector He is the dominant species above 170 km, O the dominant species from 140-170 km and CO2 the dominant species below 140 km. Estimated scale height temperatures for He, O and CO2 of about 105-120 K are similar to those observed in 1978-80 at higher solar activity. The densities at 1 am local solar time and at 150 km are within 35% of those measured earlier. The He bulge is also similar to that observed in 1978-80 confirming that thermosphere superrotation is still present. Comparison with the results of a Venus Thermosphere General Circulation Model suggests the nightside is not sensitive to changes in solar activity due to the isolation of the day and night thermospheres. Apparently, the relatively small changes in the dayside thermosphere with solar activity have little impact on the nightside thermosphere.

Kasprzak, W. T.↗
NASA NTRS1976

Electro-optical detector for use in a wide mass range mass spectrometer

An electro-optical detector is disclosed for use in a wide mass range mass spectrometer (MS), in the latter the focal plane is at or very near the exit end of the magnetic analyzer, so that a strong magnetic field of the order of 1000G or more is present at the focal plane location. The novel detector includes a microchannel electron multiplier array (MCA) which is positioned at the focal plane to convert ion beams which are focused by the MS at the focal plane into corresponding electron beams which are then accelerated to form visual images on a conductive phosphored surface. These visual images are then converted into images on the target of a vidicon camera or the like for electronic processing. Due to the strong magnetic field at the focal plane, in one embodiment of the invention, the MCA with front and back parallel ends is placed so that its front end forms an angle of not less than several degrees, preferably on the order of 10.degree.-20.degree., with respect to the focal plane, with the center line of the front end preferably located in the focal plane. In another embodiment the MCA is wedge-shaped, with its back end at an angle of about 10.degree.-20.degree. with respect to the front end. In this embodiment the MCA is placed so that its front end is located at the focal plane.

Giffin, Charles E.↗
NASA NTRS1980

Bennett ion mass spectrometers on the Pioneer Venus Bus and Orbiter

Identical Bennett radio-frequency ion mass spectrometer instruments on the Pioneer Venus Bus and Orbiter have provided the first in-situ measurements of the detailed composition of the planet's ionosphere. The sensitivity, resolution, and dynamic range are sufficient to provide measurements of the solar-wind-induced bow-shock, the ionopause, and highly structured distributions of up to 16 thermal ion species within the ionosphere. The use of adaptive scan and detection circuits and servo-controlled logic for ion mass and energy analysis permits detection of ion concentrations as low as 5 ions/cu cm and ion flow velocities as large as 9 km/sec for O(+). A variety of commandable modes provides ion sampling rates ranging from 0.1 to 1.6 sec between measurements of a single constituent. A lightweight sensor and electronics housing are features of a compact instrument package.

Taylor, H. A., Jr.↗
NASA NTRS2014

The Neutral Gas and Ion Mass Spectrometer on the Mars Atmosphere and Volatile Evolution Mission

The Neutral Gas and Ion Mass Spectrometer (NGIMS) of the Mars Atmosphere and Volatile Evolution Mission (MAVEN) is designed to measure the composition, structure, and variability of the upper atmosphere of Mars. The NGIMS complements two other instrument packages on the MAVEN spacecraft designed to characterize the neutral upper atmosphere and ionosphere of Mars and the solar wind input to this region of the atmosphere. The combined measurement set is designed to quantify atmosphere escape rates and provide input to models of the evolution of the martian atmosphere. The NGIMS is designed to measure both surface reactive and inert neutral species and ambient ions along the spacecraft track over the 125-500 km altitude region utilizing a dual ion source and a quadrupole analyzer.

Gas↗
NASA NTRS1974

Fast scan control for deflection type mass spectrometers

A high speed scan device is reported that allows most any scanning sector mass spectrometer to measure preselected gases at a very high sampling rate. The device generates a rapidly changing staircase output which is applied to the accelerator of the spectrometer and it also generates defocusing pulses that are applied to one of the deflecting plates of the spectrometer which when shorted to ground deflects the ion beam away from the collector. A defocusing pulse occurs each time there is a change in the staircase output.

Yeager, P. R.↗
NASA NTRS1986

Quadrupole mass spectrometer for Space Shuttle applications - Flight capabilities and ground calibration

The AFGL Quadrupole Ion/Neutral Mass Spectrometer (QINMS), its flight capabilities, and a few examples of QINMS data from the STS-4 flight are discussed in addition to the beam facility and calibration procedures used at the Los Alamos National Laboratory facility. A 5-eV atomic oxygen beam is produced using a continuous optical discharge technique, and the resulting pumped beam has sufficient high flux and velocity to simulate orbital conditions. The calibrated instrument will be used in the NASA Johnson Space Center Evaluation of Oxygen Interactions with Materials experiment to measure the density of ambient oxygen and to identify the products of oxygen-surface reactions.

Hunton, D. E.↗
NASA NTRS2002

Evaluation of Small Mass Spectrometer Systems

This work is aimed at understanding the aspects of designing a miniature mass spectrometer (MS) system. A multitude of commercial and government sectors, such as the military, environmental agencies and industrial manufacturers of semiconductors, refrigerants, and petroleum products, would find a small, portable, rugged and reliable MS system beneficial. Several types of small MS systems are evaluated and discussed, including linear quadrupole, quadrupole ion trap, time of flight and sector. The performance of each system in terms of accuracy, precision, limits of detection, response time, recovery time, scan rate, volume and weight is assessed. A performance scale is setup to rank each systems and an overall performance score is given to each system. All experiments involved the analysis of hydrogen, helium, oxygen and argon in a nitrogen background with the concentrations of the components of interest ranging from 0-5000 part-per-million (ppm). The relative accuracies of the systems vary from < 1% to approx. 40% with an average below 10%. Relative precisions varied from 1% to 20%, with an average below 5%. The detection limits had a large distribution, ranging from 0.2 to 170 ppm. The systems had a diverse response time ranging from 4 s to 210 s as did the recovery time with a 6 s to 210 s distribution. Most instruments had scan times near, 1 s, however one instrument exceeded 13 s. System weights varied from 9 to 52 kg and sizes from 15 x 10(exp 3)cu cm to 110 x 10(exp 3) cu cm.

Arkin, C. Richard↗
NASA NTRS1992

Role of a microbore capillary column in the development of a portable gas chromatograph-mass spectrometer

An approach to the development of a high-performance, field portable gas chromatograph-mass spectrometer is presented which is based on a combination of a short microbore capillary column and a miniaturized, light-weight focal plane mass spectrograph. Performance results of the short microbore column for the mixture separation of the major pollutants and data on time-resolved mass spectral measurements of overlapped gas chromatograph peaks are reported.

Sinha, Mahadeva P.↗
NASA NTRS2012

Laser Ablation Mass Spectrometer (LAMS) as a Standoff Analyzer in Space Missions for Airless Bodies

A laser ablation mass spectrometer (LAMS) based on a time-of-flight (TOF) analyzer with adjustable drift length is proposed as a standoff elemental composition sensor for space missions to airless bodies. It is found that the use of a retarding potential analyzer in combination with a two-stage reflectron enables LAMS to be operated at variable drift length. For field-free drift lengths between 33 cm to 100 cm, at least unit mass resolution can be maintained solely by adjustment of internal voltages, and without resorting to drastic reductions in sensitivity. Therefore, LAMS should be able to be mounted on a robotic arm and analyze samples at standoff distances of up to several tens of cm, permitting high operational flexibility and wide area coverage of heterogeneous regolith on airless bodies.

Li, X.↗
NASA NTRS1974

The use of the ion probe mass spectrometer in the measurement of hydrogen concentration gradients in Monel K 500

The ion probe mass spectrometer was used to measure hydrogen concentration gradients in cathodically charged Monel K 500. Initial work with the ion probe involved the calibration of the instrument and the establishment of a suitable experimental procedure for this application. Samples of Monel K 500 were cathodically charged in a weak sulfuric acid solution. By varying the current density, different levels of hydrogen were introduced into the samples. Hydrogen concentration gradients were taken by ion sputtering on the surface of these samples and monitoring the behavior of the hydrogen mass peak as a function of time. An attempt was made to determine the relative amounts of hydrogen in the bulk and grain boundaries by analyzing a fresh fracture surface with a higher proportion of grain boundary area. It was found that substantially more hydrogen was detected in the grain boundaries than in the bulk, confirming the predictions of previous workers. A sputter rate determination was made in order to establish the rate of erosion.

Truhan, J. J., Jr.↗
NASA NTRS1992

Observations of plasma dynamics in the coma of P/Halley by the Giotto ion mass spectrometer

The paper reports observations of plasma dynamics in the coma of P/Halley by the Giotto ion mass spectrometer. Measurements of protons and alpha particles from the far upstream region to the near ionopause region and of ions of mass 12-32 at distances of about 250,000 to 40,000 km from the nucleus are presented. The discontinuity known as the magnetic pileup boundary (MPB) is apparent only in proton, alpha particle, and magnetometer data, indicating that it is a tangential discontinuity of solar wind origin. No significant change is found in the properties of the heavy ions across the MPB. The issue of whether a cometopause was unambiguously observed at Comet Halley is discussed; it is concluded that the observations do not convincingly support the idea of a boundary due to internal cometary processes. A comparison of the observations to MHD models is made. The plasma flow directions at all distances greater than 30,000 km from the nucleus are in agreement with MHD calculations.

Goldstein, B. E.↗