SEARCH · Engineering Papers
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Measurements of electron density in the lower ionosphere were made at White Sands Missile Range throughout the STRATCOM VIII launch day using a partial-reflection sounder. Information regarding the sounder's antenna pattern was gained from the passage of the balloon over the array.
Progress is reported in the following areas: D-region theory; E and F-region; wave propagation; mass spectrometer measurements; and atmospheric reactions. Various supporting operations are included: design and construction of instrumentation; and programming.
Rocket sounding measurements of ionospheric D region electron density profile during 20 May 1966 solar eclipse, discussing D region ionization source
The state of the ionosphere above stations in Kazakhstan is examined in connection with the proton flares of 7 July, 28 August, and 2 September 1966. Universal time is used. It is established that a proton flare causes increased radio absorption (the ionization of the D-region is enhanced, and the minimum reflected frequencies decrease). Magnetic storms and ionospheric disturbances are observed on the earth one-and-a-half to two days after some proton flares.
Introduction, organization, analyses, conclusions, and recommendations for each of the spaceborne subsystems are presented. Environmental effects - propagation analyses are presented with appendices covering radio wave diffraction by random ionospheric irregularities, self-focusing plasma instabilities and ohmic heating of the D-region. Analyses of dc to rf conversion subsystems and system considerations for both the amplitron and the klystron are included with appendices for the klystron covering cavity circuit calculations, output power of the solenoid-focused klystron, thermal control system, and confined flow focusing of a relativistic beam. The photovoltaic power source characteristics are discussed as they apply to interfacing with the power distribution flow paths, magnetic field interaction, dc to rf converter protection, power distribution including estimates for the power budget, weights, and costs. Analyses for the transmitting antenna consider the aperture illumination and size, with associated efficiencies and ground power distributions. Analyses of subarray types and dimensions, attitude error, flatness, phase error, subarray layout, frequency tolerance, attenuation, waveguide dimensional tolerances, mechanical including thermal considerations are included. Implications associated with transportation, assembly and packaging, attitude control and alignment are discussed. The phase front control subsystem, including both ground based pilot signal driven adaptive and ground command approaches with their associated phase errors, are analyzed.
A review is made of ionospheric data reported since the IGY from rocket and satellite-borne ionospheric experiments. These include rocket results on electron density (RF impedance probe), D-region conductivity (Gerdien condenser), and electron temperature (Langmuir probe). Also included are data in the 1000 kilometer region on ion concentration (ion current monitor) and electron temperature from the Explorer VIII Satellite (1960 xi). The review includes suggestions for second generation experiments and combinations thereof particularly suited for small sounding rockets.
This paper reviews the ground-based and rocket techniques that are presently being used to determine electron density profiles in the ionospheric D region. Ground-based techniques include VLF, LF, and MF sounding; differential absorption and differential phase measurements using partial reflections; wave interaction; and incoherent scatter. Rocket techniques include differential absorption and Faraday rotation in association with high-resolution dc probes calibrated by means of the radio measurements. The characteristics of the aforementioned techniques are presented, including time and height resolution, accuracy estimates, preferred height ranges, and problems encountered. Electron density profiles obtained with these techniques are presented for comparable solar zenith angles and undisturbed solar and geophysical conditions.
Electron density measurements made with the partial reflections technique above Urbana, Illinois (44 deg 10 min N, 88 deg 10 min W) were analyzed for day-to-day variations, seasonal variations, magnetic storm aftereffects, and stratosphere-ionosphere coupling effects. As well as showing a winter anomaly, the electron densities near 76 km were significantly lower in fall than in spring. Magnetic storm aftereffects of the type predicted by models of energetic electron precipitation at middle latitudes were observed. No strong correlations were found between stratospheric and D-region time series, or between the occurrence of stratospheric warmings and D-region changes. It is likely that most of the electron density variation was due to variations in the transport of minor neutral constituents. The spring-fall differences were also probably caused by differences in minor constituent concentrations rather than the effect of temperature changes on the recombination coefficient.
The flow of weakly ionized plasmas that is similar to the flow that occurs over rocket-borne blunt probes as they pass through the lower ionosphere has been simulated in a scaled laboratory environment, and electron collection D region blunt probe theories have been evaluated.
Rocket measurement of quiet D-region electron number density profiles near sunrise
An extensive series of vertical incidence absorption measurements made at an equatorial station is analyzed in detail to provide information which will lead to a better understanding of the lower ionosphere. A quantitative empirical relationship is derived between absorption and 1-8 A solar flux for moderate levels of solar activity. It is shown that the threshold flux for D-region modification, at a solar zenith angle of 10 deg, is approximately 0.0005 erg per sq cm per sec. Attention is drawn to the incidence of days of high absorption even in the absence of solar X-ray activity. Available evidence points to variability of the order of 10-40 per cent in the intensity of the solar Lyman-alpha radiation as the most likely cause of these unusual, though infrequent, enhancements in absorption.
Subsonic probe for measurement of charged particle densities in D layer of ionosphere
D region electron density profiles and corpuscular radiation measured by DC probe and Geiger counter
First-order correction to Hoult theory for measuring ion density in D region, especially those involving heat transfer and compressibility
Ion mass spectrometry of D layer, using magnetic fields and cyclotron resonance principle
Number densities of ions and electrons in D region measured, using Arcas rocket
Weak shock effects and chemistry of lower D region, and blunt supersonic probe theory and first order corrections
D-region mobility and constituents abundance spectrometer device based on continuum concepts