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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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Measurement of low-intensity electric fields in space and in presence of weak magnetic fields is accomplished by utilizing a device which permits determination of the extent a beam of cesium ions is deflected by an electric field.
Electric field measuring methods, showing Stark effect in rotational spectra of gases as most promising
For a summer thunderstorm, for which simultaneous, airborne electric field measurements and Lightning Detection and Ranging (LDAR) System data was available, measurements were coordinated to present a picture of the electric field intensity near cloud electrical discharges detected by the LDAR System. Radar precipitation echos from NOAA's 10 cm weather radar and measured airborne electric field intensities were superimposed on LDAR PPI plots to present a coordinated data picture of thunderstorm activity.
New method for mounting thin sample for electrical measurements involves use of vacuum chuck to hold a ceramic mounting plate, which holds sample. Contacts on mounting plate establish electrical connection to sample. Used to make electrical measurements over temperature range from 77 to 1,000 K and does not introduce distortions into magnetic field during Hall measurements.
Simple electric field measuring system is mounted on small rocket and consists of two voltage probes, one extending from nose and other on tail fin. Electric field through which rocket passes is determined by potential difference between probes.
Automatic control systems and electric measurement of nonelectric quantities in data processing related to theoretical considerations, space flights, and production engineering
Measuring electrical conductivity of plasma with magnetic probe
Electron beam deflection devices for measuring electric fields
Deflection of electron beam as means for measuring electric field strength
A method for mounting thin samples for electrical measurements is described. The technique is based on a vacuum chuck concept in which the vacuum chuck simultaneously holds the sample and established electrical contact. The mounting plate is composed of a glass-ceramic insulating material and the surfaces of the plate and vacuum chuck are polished. The operation of the vacuum chuck is examined. The contacts on the sample and mounting plate, which are sputter-deposited through metal masks, are analyzed. The mounting method was utilized for van der Pauw measurements.
An apparatus for measuring the electric field in the atmosphere which includes a pair of sensors carried on a rocket for sensing the voltages in the atmosphere being measured is described. One of the sensors is an elongated probe with a fine point which causes a corona current to be produced as it passes through the electric field. An electric circuit is coupled between the probe and the other sensor and includes a high ohm resistor which linearizes the relationship between the corona current and the electric field being measured. A relaxation oscillator and transmitter are provided for generating and transmitting an electric signal having a frequency corresponding to the magnitude of the electric field.
The development of a rocket borne instrument to measure electric fields in thunderstorms is described. Corona currents from a sharp needle atop a small rocket are used to sense the electric field. A high ohm resistor in series with the corona needle linearizes the relationship between corona current and electric field. The corona current feeds a relaxation oscillator, whose pulses trigger a transmitter which operates in the 395 to 410 MHz meteorological band. The instrument senses fields between 5 kV/m and 100 kV/m.
A novel method of mounting thin samples for electrical measurements is described. A vacuum chuck holds a mounting plate, which, in turn, holds the sample. Contacts on the mounting plate establish electrical connection to the sample. The attachment of wires directly to the samples is unnecessary. Measurements can be made at temperatures from 77 to 1000 K. As an application of the apparatus, resistivity and Hall measurements of a thin silicon carbide sample are presented.
Slightly modified micrometer used in conjunction with special cup to measure electrical resistance of specimen of powder as function of packing fraction. Powder pressed between anvils of micrometer, which make electrical contact with specimen. Device used in manufacturing batteries to determine effective electrical conductivities of powders loaded into plastic sheets to make battery substrates. Coupled with good mathematical description of expected conductivity of particulate composite as function of packing density. Also serves as tool for evaluating conductivity of dispersed phase, as well as evaluating electrical resistances of interparticle contacts.
On August 9, 1981, a series of three rockets was launched over an air mass thunderstorm off the eastern seaboard of Virginia while simultaneous stratospheric and ground-based electric field measurements were made. The conductivity was substantially lower at most altitudes than the conductivity profiles used by theoretical models. Direct current electric fields over 80 mV/m were measured as far away as 96 km from the storm in the stratosphere at 23 km altitude. No dc electric fields above 75 km altitude could be identified with the thunderstorm, in agreement with theory. However, vertical current densities over 120 pA/sq m were seen well above the classical 'electrosphere' (at 50 or 60 km). Frequent dc shifts in the electric field following lightning transients were seen by both balloon and rocket payloads. These dc shifts are clearly identifiable with either cloud-to-ground (increases) or intercloud (decreases) lightning flashes.
As part of the Flat-Plate Solar Array Project, 138 different module designs were subjected to qualification tests. Electrical measurements were subjected on well over a thousand modules representing more than 150 designs. From this experience, conclusions are drawn regarding results and problems, with discussion of the need for change or improvement. The qualification test sequence incuded application of environmental and electrical stresses to the module. With few exceptions, the tests have revealed defects necessitation of environmental and electrical stresses to the module. With few exceptions, the tests have revealed defects necessitating module design or process changes. However, the continued need for these tests may be questioned on the basis of technical and logistical factors. Technically, the current test sequence does not cover all design characteristics, does not include all field conditions and is not known to represent the desired 30-year module life. Logistically, the tests are time-consuming and costly, and there is a lack of, fully qualified independent test organizations. Alternatives to the current test program include simplification based on design specification and site environment, and/or the use of warranties or other commercial practices.
A balloon-borne experiment to measure the atmospheric electric field was flown from the National Scientific Balloon Facility at Palestine, Texas, on July 10, 1973. The electric field and atmospheric conductivity were measured during ascent and for a 4-hour float period at 37-km altitude. Termination of the flight occurred near a thunderstorm line in west Texas. The perturbing influence of the thunderstorms on the electric field was observed at least 100 km from the storm line. The measured electric field is in reasonable agreement with calculations based on simple models of cloud structure and atmospheric conductivity. Large pulses in the measured electric field are interpreted as being the result of intracloud lightning.
Electrical noise measurement system measures noise generated by edge-type connectors and circuit cards when they are subjected to sinusoidal vibration. It provides a signal across the contact area and monitors the signal change during vibration. Noise measured can be expressed as a varying change in total contact resistance.