Oscillating fiber microbalance.
Oscillating fiber microbalance for direct mass determinations in .1 mg to .0001 microgram range
Hemenway, C. L.↗
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Microbalance accurately measures extremely small masses
Oscillating fiber microbalance has a vibrating quartz fiber as balance arm to hold the mass to be weighed. Increasing fiber weight decreases its resonant frequency. Scaler and timer measure magnitude of the shift. This instrument withstands considerable physical abuse and has calibration stability at normal room temperatures.
Patashnick, H.↗
Null-type vacuum microbalance Patent
Null-type vacuum microbalance for measuring minute mechanical displacements
Rogallo, V. L.↗
Quartz crystal microbalance use in biological studies
Design, development, and applications of quartz crystal microbalance are discussed. Two types of crystals are used. One serves as reference and other senses changes in mass. Specific application to study of bacterial spores is described.
Green, R. H.↗
A Comparison of Quartz Crystal Microbalance Measurements with Mass Spectrometer Determinations
An experimental program was undertaken in which mass accretion rates, as determined by a liquid nitrogen cooled quartz crystal microbalance, were compared with the mass flux rates, as determined by both a cycloidal type and a quadrupole type residual gas analyzer for five simple materials. The data indicate a high degree of correlation between these instruments insofar as the shape of the curves. There are large variations however among the absolute values.
Kruger, R.↗
Plume backscatter measurements using quartz crystal microbalances in JPL Molsink (molecular sink)
Quantitative evidence of gas flows in the far upstream region of small nozzles with large boundary layer flow are discussed. Gas mass fluxes were measured using quartz crystal microbalances. Both nitrogen and carbon dioxide gases were used as test gases. Gas deposition rates on the order of 100 monolayers per minute were detected 13 inches upstream of the nozzle exit plane. It is significant to note that the crystals detected gases considerably beyond the Prandtl-Meyer turning angle. The data from these tests will be essential in the formulation of scaling laws and analytical prediction methods for viscous plume behavior.
Simon, W.↗
Quartz crystal microbalance contamination monitors on Skylab: A quick look analysis
Six quartz crystal microbalance contamination monitors were flown on Skylab to monitor the deposition of material from spacecraft outgassing and from the rendezvous and docking maneuvers of the Command/Service Module. This report contains a quick-look analysis of the data from these units during the unmanned and manned portions of SL2.
Naumann, R.↗
Molecular fluxes from a spacecraft measured with quartz microbalances
A technique has been developed to obtain a characterization of the self-generated environment of a spacecraft and its variation with time, angular position, and distance. The density, pressure, outgassing flux, total weight loss, and other important parameters were obtained from data provided by two mass measuring crystal microbalances, mounted back to back, at a distance of 1 m from the spacecraft equivalent surface. The strongest source appeared to be caused by a material diffusion process which produced a directional density at 1 m distance of about 160 billion molecules per cu cm after 1 h in vacuum and decayed to 1.6 billion molecules per cu cm after 200 h. Self-contamination of the spacecraft was equivalent to that which occurs in a 300-km altitude orbit.
Scialdone, J. J.↗
Data from a synchronous altitude satellite quartz crystal microbalance monitor
Results of one year's operation in orbit of the Quartz Crystal Microbalance Monitor on the ATS-6 satellite are presented. The data indicate a general decreasing trend for the first four and one-half months in orbit. At that time, a sudden increase in beat frequency occurred; this correlates in time with the firing of the North Cesium Ion Engine. A general increase in beat frequency is evidenced since that time. Laboratory tests conducted to investigate the phenomenon are described.
Rogers, J. F.↗
Feasibility demonstration for hydrogen chloride detection using a chemisorption technique and a quartz crystal microbalance
A method of measuring concentrations of hydrogen chloride between 1 part per billion and 10 parts per million at standard temperature and pressure is presented. The feasibility of a low-cost device incorporating a chemisorption technique coupled with a quartz crystal microbalance was demonstrated in the field at the Viking B launch using a Titan-Centaur vehicle from Kennedy Space Center on August 20, 1975. Hydrogen chloride is a product of solid rocket combustion. The concentration level of hydrogen chloride for this particular launch was measured as approximately 0.2 parts per million at 4 km from the launch site.
Jex, D. W.↗
ATS-6 - Quartz-Crystal Microbalance
The Quartz-Crystal Microbalance Experiment provided data on the possible return of contaminants to the exterior surfaces of the spacecraft. The experiment measures the change in resonant frequency of the crystal due to deposition of material on the surface. There has been no mass accretion corresponding to the firing of hydrazine thrusters to unload the spacecraft momentum wheels. There have been accretions corresponding to the firing of the cesium ion engines.
Rogers, J. F.↗
Development of a microbalance suitable for space application
The tapered element oscillating microbalance (TEOM), an ultrasensitive mass measurement device which is suitable for both particulate and vapor deposition measurements is described. The device can be used in contamination measurements, surface reaction studies, particulate monitoring systems or any microweighing activity where either laboratory or field monitoring capability is desired. The active element of the TEOM consists of a tube or reed constructed of a material with high mechanical quality factor and having a special taper. The element is firmly mounted at the wide end while the other end supports a substrate surface which can be composed of virtually any material. The tapered element with the substrate at the free (narrow) end is set into oscillation in a clamped free mode. A feedback system maintains the oscillation whose natural frequency will change in relation to the mass deposited on the substrate.
Patashnick, H.↗
Quartz Crystal Microbalance (QCM) monitor of contamination for LES-8/9
A Quartz Crystal Microbalance (QCM) was used to monitor condensable contamination during the launching of two Lincoln Laboratory Experimental Satellites--LES-8 and LES-9. The QCM was installed on the dispenser truss and measured contamination by means of a frequency shift of a quartz crystal oscillator. By using a special crystal cut and a second reference quartz crystal, the sensor had extreme sensitivity and remarkable temperature independence. A 1-Hz frequency shift, which corresponds to 3.5 x 10 to the -9th power g/sq cm was resolved by the flight instrumentation.
Lynch, J. T.↗
The Response of a Quartz Crystal Microbalance to a Liquid Deposit
A theory was developed for predicting the loss of response of a QCM (Quartz Crystal Microbalance) to a liquid deposit due to viscous effects in the deposit. The loss of response is expressed by a response factor, equal to the response of the QCM to a liquid film divided by its response to a solid film of the same mass per unit area. The theory assumes a droplet-type deposit morphology, and considers the influence of droplet distribution parameters. Experiments were conducted to examine the validity of the theory, using DC 704 silicone oil as the subject deposit material. Experiments were made in two series: one with constant deposit mass and variable temperature, the other with variable deposit mass and constant temperature. Interpretation of the data using the theory has enabled information on droplet area coverage and number density to be deduced.
Glassford, A. P. M.↗
The calibration of the quartz crystal microbalance cascade impactor using the berglund-liu monodisperse aerosol generator for aerosol studies in the atmosphere
The Quartz Crystal Microbalance was calibrated and its response to particle size and mass concentration was determined.
Matthews, N.↗
Rocket effluent size distributions made with a cascade quartz crystal microbalance
Airborne particulate size distribution measurements were made in the stabilized ground cloud from a Titan III C rocket just after launch from the Kennedy Space Center on May 12, 1977. The measurements were made from aboard a small twin engine aircraft instrumented with particle and gas sensors. The plume was followed for about 1 hour while making multiple passes through the cloud at varying altitudes. The results obtained with a ten-stage cascade quartz crystal microbalance impactor show that the mass concentration as a function of particle diameter is bimodal with the first maximum between 0.05 micrometers and 0.1 micrometers and the second maximum between 0.8 and 1.0 micrometer. Scanning electron microscope analysis were performed on the material collected and show distinctly different kinds of particles in the two modes.
Woods, D. C.↗
Flight evidence of spacecraft surface contamination rate enhancement by spacecraft charging obtained with a quartz crystal microbalance
The significance of the fraction of the mass outgassed by a negatively charged space vehicle which is ionized within the vehicle plasma sheath and electrostatically reattracted to the space vehicle was determined. The ML-12 retarding potential analyzer/temperature controlled quartz crystal microbalances (RPA/TQCMs) distinguishes between charged and neutral molecules and investigates contamination mass transport mechanism. Two long term, quick look flight data sets indicate that on the average a significant fraction of mass arriving at one RPA/TQCM is ionized. It is assumed that vehicle frame charging during these periods was approximately uniformly distributed in degree and frequency. It is shown that electrostatic reattraction of ionized molecules is an important contamination mechanism at and near geosynchronous altitudes.
Clark, D. M.↗
A temperature control design for a tapered element oscillating microbalance sensing surface
A design study is presented which shows that a tapered element oscillating microbalance can be adapted for temperature control under space application by mating with multistage thermoelectric coolers in such a way that an integral structure evolves. The control of the temperature of the sensing surface can be achieved in a number of ways. An indirect method which uses a measurement of the absorbed power is recommended. The design goals can be met if a relaxation of the power requirement can be considered.
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