Rocket measurements of midlatitude Sq currents
Nike-Apache rocket ionospheric current measurements using rubidium-vapor magnetometer
NIKE ROCKET↗
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Results for “Current measurement”
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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Ring current particle distributions derived from ring current magnetic field measurements.
Ring current particle energy density distribution for symmetric portion of magnetic storm derived from current magnetic field profile measurements
Cahill, L. J., Jr.↗
Fiber-Optic Ammeter
In addition to fiber-optic loop, apparatus includes stable source of coherent light and high-resolution optical receiver. Magnetic field generated by electric current measured via Faraday effect. Developed to measure electric currents and/or magnetic fields in outer space as part of effort to determine number densities and directions of movement of electrically charged particles; loop of low-loss optical fiber made large enough so number of charged particles encircled adaquate for measurement. Apparatus also used on Earth in noncontact measurements of electric currents.
Wyntjes, Geert↗
Optically isolated logarithmic nanoammeter capable of floating to 5 kilovolts
A logarithmic current-measuring instrument was developed to measure plasma coupling currents at a common mode voltage of 5 kilovolts. Positive or negative currents can be measured from 10 to the -9th power to .001 ampere direct current. Optical isolation is used to control input switching and to provide data referenced to ground potential. Analog meter readouts as well as zero to five volt outputs are provided for peripheral data collection. Six independent channels are provided. Three measure positive currents, and three measure negative currents. Although designed for vacuum operation, it can be used equally well in air to measure low currents at high common mode voltages.
Sturman, J. C.↗
Miniature Rogowski coil probes for direct measurement of current density distributions in transient plasmas.
Miniature Rogowski coil probes for direct measurement of current density distributions in transient plasmas
ELECTRIC MEASUREMENT↗
Proposal for an astronaut mass measurement device for the Space Shuttle
For medical reasons, astronauts in space need to have their mass measured. Currently, this measurement is performed using a mass-spring system. The current system is large, inaccurate, and uncomfortable for the astronauts. NASA is looking for new, different, and preferably better ways to perform this measurement process. After careful analysis our design team decided on a linear acceleration process. Within the process, four possible concept variants are put forth. Among these four variants, one is suggested over the others. The variant suggested is that of a motor-winch system to linearly accelerate the astronaut. From acceleration and force measurements of the process combined Newton's second law, the mass of an astronaut can be calculated.
Beyer, Neil↗
Current Density Measurements of an Annular-Geometry Ion Engine
The concept of the annular-geometry ion engine, or AGI-Engine, has been shown to have many potential benefits when scaling electric propulsion technologies to higher power. However, the necessary asymmetric location of the discharge cathode away from thruster centerline could potentially lead to non-uniformities in the discharge not present in conventional geometry ion thrusters. In an effort to characterize the degree of this potential nonuniformity, a number of current density measurements were taken on a breadboard AGI-Engine. Fourteen button probes were used to measure the ion current density of the discharge along a perforated electrode that replaced the ion optics during conditions of simulated beam extraction. Three Faraday probes spaced apart in the vertical direction were also used in a separate test to interrogate the plume of the AGI-Engine during true beam extraction. It was determined that both the discharge and the plume of the AGI-Engine are highly uniform, with variations under most conditions limited to 10% of the average current density in the discharge and 5% of the average current density in the plume. Beam flatness parameter measured 30 mm from the ion optics ranged from 0.85 0.95, and overall uniformity was shown to generally increase with increasing discharge and beam currents. These measurements indicate that the plasma is highly uniform despite the asymmetric location of the discharge cathode.
Shastry, Rohit↗
Current Density Measurements of an Annular-Geometry Ion Engine
The concept of the annular-geometry ion engine, or AGI-Engine, has been shown to have many potential benefits when scaling electric propulsion technologies to higher power. However, the necessary asymmetric location of the discharge cathode away from thruster centerline could potentially lead to non-uniformities in the discharge not present in conventional geometry ion thrusters. In an effort to characterize the degree of this potential non-uniformity, a number of current density measurements were taken on a breadboard AGI-Engine. Fourteen button probes were used to measure the ion current density of the discharge along a perforated electrode that replaced the ion optics during conditions of simulated beam extraction. Three Faraday probes spaced apart in the vertical direction were also used in a separate test to interrogate the plume of the AGI-Engine during true beam extraction. It was determined that both the discharge and the plume of the AGI-Engine are highly uniform, with variations under most conditions limited to +/-10% of the average current density in the discharge and +/-5% of the average current density in the plume. Beam flatness parameter measured 30 mm from the ion optics ranged from 0.85 - 0.95, and overall uniformity was shown to generally increase with increasing discharge and beam currents. These measurements indicate that the plasma is highly uniform despite the asymmetric location of the discharge cathode.
Shastry, Rohit↗
Eddy current probe measures size of cracks in nonmetallic materials
Nondestructive method uses powdered iron and eddy current probe to measure the depth/width ratio of cracks in electrically nonconductive materials. The eddy current probe measures the mass of metal in the crack after it has been filled with the powdered iron.
Musser, C. W.↗
Microgravity combustion discipline working group summary of requirements for noncontact temperature measurements
Current efforts of the Microgravity Combustion Working Group are summarized and the temperature measurement requirements for the combustion studies are defined. Many of the combustion systems that are studied in the low gravity environment are near-limit systems, that is, systems that are acting near the limit of flammability in terms of oxygen concentration or fuel concentration. Systems of this type are normally weak in the sense that there is a delicate balance between the heat released in the flame and the heat required to sustain the flame. Intrusive or perturbative temperature measurement probes can be inaccurate in these situations and in the limiting case extinguish the flame. Noncontact techniques then become the only way to obtain the required measurements. Noncontact measurement requirements for each of the three thermodynamic phases are described in terms of spatial and temporal resolution and temperature range.
Sacksteder, Kurt↗
"Fuel Gage" for Electric Vehicles
Gas-emmission and time-integrated-current measurements indicate battery charge state. Tests indicate possibility of monitoring state of charge of lead/acid batteries at any stage in charging cycle by measuring charging current and either gas evolution or electrode potential. Data then processed by microcomputer. Uses include cell voltage, cell pressure, cell temperature and rate of gas recombination on catalyst.
Rowlette, J. J.↗
Axial current density measurements in a wide unstable plasma column.
Wide argon plasma column by axial current density measurements, confirming existence of instability and determining critical magnetic field
Smith, N. K.↗
Farfield Ion Current Density Measurements before and after the NASA HiVHAc EDU2 Vibration Test
There is an increasing need to characterize the plasma plume of the NASA HiVHAc thruster in order to better understand the plasma physics and to obtain data for spacecraft interaction studies. To address this need, the HiVHAc research team is in the process of developing a number of plume diagnostic systems. This paper presents the initial results of the farfield current density probe diagnostic system. Farfield current density measurements were carried out before and after a vibration test of the HiVHAc engineering development unit 2 that simulate typical launch conditions. The main purposes of the current density measurements were to evaluate the thruster plume divergence and to investigate any changes in the plasma plume that may occur as a result of the vibration test. Radial sweeps, as opposed to the traditional polar sweeps, were performed during these tests. The charged-weighted divergence angles were found to vary from 16 to 28 degrees. Charge density profiles measured pre- and post-vibration-test were found to be in excellent agreement. This result, alongside thrust measurements reported in a companion paper, confirm that the operation of the HiVHAc engineering development unit 2 were not altered by full-level/random vibration testing.
Huang, Wensheng↗
Effects of solution mass transport on the ECC ozonesonde background current
Measurement of the mass transport rate constant for the electrochemical concentration cell in an ozonesonde as a function of the pressure is reported. The investigation was performed to accurately model the residual current present in the ECC cell in the absence of ozone. The convective mass transport for two sondes were determined while maintaining a sufficiently negative cathodic potential to eliminate electron transfer at the cathode surface. A sonde was placed in a bell jar and subjected to varying pressure levels. When the background current was kept below 0.1 microamp and pressure was from 100-1000 mb, the necessary correction term for the pressure was independent of pressure. However, below 100 mb, a logarithmic decrease in the background current with pressure is expected. Present practices, involving a sensitivity to oxygen, are calculated to result in overestimation of the total ozone between 1000-10 mb by 0.0096 atm-cm with a background current of 0.1 microamp at 1000 mb.
Thornton, D. C.↗
Medium and large-scale variations of dynamo-induced electric fields from AE ion drift measurements
Current models of the low latitude electric field are largely based on data from incoherent scatter radars. These observations are extended through the addition of the rather extensive high quality electric field measurements from the Ion Drift Meter (IDM) aboard the Atmosphere Explorer (AE) spacecraft. Some preliminary results obtained from the Unified Abstract files of satellite AE-E are presented. This satellite was active from the end of 1975 through June 1981 in various elliptical and circular orbits having an inclination near 20 deg. The resulting data can be examined for the variation of ion drift with latitude, longitude, season, solar cycle, altitude, and magnetic activity. The results presented deal primarily with latitudinal variations of the drift features. Diagrams of data are given and briefly interpreted. The preliminary results presented here indicate that IDM data from the AE and the more recent Dynamics Explorer B spacecraft should continue to disclose some interesting and previously unobserved dynamical features of the low latitude F region.
Coley, W. R.↗
Assessment of Vegetation Stress Using Reflectance or Fluorescence Measurements
Current methods for large-scale vegetation monitoring rely on multispectral remote sensing, which has serious limitation for the detection of vegetation stress. To contribute to the establishment of a generalized spectral approach for vegetation stress detection, this study compares the ability of high-spectral resolution reflectance (R) and fluorescence (F) foliar measurements to detect vegetation changes associated with common environmental factors affecting plant growth and productivity. To obtain a spectral dataset from a broad range of species and stress conditions, plant material from three experiments was examined, including (i) corn, nitrogen (N) deficiency/excess; (ii) soybean, elevated carbon dioxide, and ozone levels; and (iii) red maple, augmented ultraviolet irradiation. Fluorescence and R spectra (400-800 nm) were measured on the same foliar samples in conjunction with photosynthetic pigments, carbon, and N content For separation of a wide range of treatment levels, hyperspectral (5-10 nm) R indices were superior compared with F or broadband R indices, with the derivative parameters optimal results. For the detection of changes in vegetation physiology, hyperspectral indices can provide a significant improvement over broadband indices. The relationship of treatment levels to R was linear, whereas that to F was curvilinear. Using reflectance measurements, it was not possible to identify the unstressed vegetation condition, which was accomplished in all three experiments using F indices. Large-scale monitoring of vegetation condition and the detection of vegetation stress could be improved by using hyperspectral R and F information, a possible strategy for future remote sensing missions.
Campbell, P. K. E.↗
Acceleration of energetic oxygen (E greater than 137 keV) in the storm-time ring current
Measurements obtained with the medium-energy particle analyzer of the equatorial-orbit AMPTE/CCE satellite during a geomagnetic storm on September 4-7, 1984 are reported and analyzed, with a focus on the high-energy populations (H, He, and CNO-group ions with E greater than 56, 72, and 137 keV, respectively). During the main phase of the storm, ring-current-region increases in O(+) intensity by factors up to 2000 are observed at L = 2.5-7.0, and the component at L = 3.5-5.5 is attributed to a 1.5-earth-radius inward displacement of the prestorm energetic-oxygen population followed by betatron acceleration. Alternative oxygen sources and/or acceleration mechanisms to account for the component at L = 6.5-8 and pitch angle 90 deg are discussed.
Lui, A. T. Y.↗
Low Velocity Difference Thermal Shear Layer Mixing Rate Measurements
Current CFD modeling techniques are known to do a poor job of predicting the mixing rate and persistence of slot film flow in co-annular flowing ducts with relatively small velocity differences but large thermal gradients. A co-annular test was devised to empirically determine the mixing rate of slot film flow in a constant area circular duct (D approx. 1ft, L approx. 10ft). The axial rate of wall heat-up is a sensitive measure of the mixing rate of the two flows. The inflow conditions were varied to simulate a variety of conditions characteristic of moderate by-pass ratio engines. A series of air temperature measurements near the duct wall provided a straightforward means to measure the axial temperature distribution and thus infer the mixing rate. This data provides a characterization of the slot film mixing rates encountered in typical jet engine environments. The experimental geometry and entrance conditions, along with the sensitivity of the results as the entrance conditions vary, make this a good test for turbulence models in a regime important to modern air-breathing propulsion research and development.
Bush, Robert H.↗