Search NASA⌕ Search

SEARCH · Search NASA

Results for “ELECTRON INTENSITY”

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.

At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Solar modulation and interplanetary gradients of the galactic electrons flux, 1977 - 1984

The flux of electrons with energy from approx. 10 to 180 MeV measured with the electron telescope on the Voyager 1 and 2 spacecraft in the heliocentric radial range 1 - 22 AU between 1977 and 1984 is reported. Jovian electrons were clearly observable between 1978 and 1983 (radial range 2 - 12 AU) at energies below approx. 50 MeV. Above approx. 50 MeV the electron intensity exhibited temporal variations generally related to the 11 year modulation of protons 75 MeV. The overall magnitude of the electron intensity changes between the maximum intensity observed in 1977 and the minimum intensity in 1981 was a factor approx. 2, also comparable to that observed for 75 MeV protons. By early 1985 the electron intensity had apparently recovered to the level observed in 1977 whereas the proton intensity was still about 20% lower. A detailed interpretation of these electron variations in all energy channels depends on an accurate subtraction of background induced by energetic protons of a few 100 MeV. This subtraction is facilitated by calibration results at several energies.

Christon, S. P.↗
NASA NTRS1977

Energization pf polar-cusp electrons at the noon meridian

Observations gained with an electrostatic analyzer on board the low altitude, polar orbiting Aeriel 4 satellite demonstrate that the directional, differential spectra of polar-cusp electron intensities are regulated by the sign of the interplanetary magnetic field (IMF) elevation angle. In the energy range 200 is approximately less than E is approximately less than 700 eV, spectra of polar cusp electron intensities were not observed to respond to changes in the sign of the IMF elevation angle. At greater densities, spectra were found to be significantly harder when the IMF angle of elevation was greater than 0 deg, with a factor of approximately 10 typical for 2-keV electron intensities. These enhanced intensities appear to be localized within approximately a one hour sector of magnetic local time centered on the noon meridian.

Craven, J. D.↗
NASA NTRS1972

Local-time survey of plasma at low altitudes over the auroral zones.

Local-time survey of the low-energy proton and electron intensities precipitated into the earth's atmosphere over the auroral zones during periods of magnetic quiescence. This survey was constructed by selecting a typical individual satellite crossing of this region in each of eight local-time sectors from a large library of similar observations with the polar-orbiting satellite Injun 5. The trapping boundary for more-energetic electron intensities, E greater than 45 keV, was found to be a 'natural coordinate' for delineating the boundary between the two major types of lower-energy, 50 less than or equal to E less than or equal to 15,000 eV, electron precipitation commonly observed over the auroral zones at low altitudes. Poleward of this trapping boundary inverted 'V' electron precipitation bands are observed in all local-time sectors. These inverted 'V' electron bands in the evening and midnight sectors are typically more energetic and have greater latitudinal widths than their counterparts in the noon and morning sectors. In general, the main contributors to the electron energy influx into the earth's atmosphere over the auroral zones are the electron inverted 'V' precipitation poleward of the trapping boundary in late evening, the plasma-sheet electron intensities equatorward of this boundary in early morning, and both of these precipitation events near local midnight.

Frank, L. A.↗
NASA NTRS1976

V.L.F. emission from ring-current electrons

Characteristics of VLF emissions detected by satellite in association with enhancements of ring-current electrons during magnetic storms and substorms are described along with the associated enhancements in electron intensities and the anisotropies of the ring-current electron distribution. It is shown that the emissions are observed only when the satellite is outside the plasmasphere, that the beginning of the emissions coincides with the satellite's encounter with the large electron fluxes in that region, and that the increase in electron intensities associated with the observed emissions is limited only to low-energy electrons. The frequency distributions of emissions with peak frequencies above and below half the electron gyrofrequency at the equator is analyzed. The bimodal frequency distribution of the equatorial whistler-mode emissions is explained in terms of different production regions for emissions at frequencies above and below half the equatorial electron gyrofrequency.

Maeda, K.↗
NASA NTRS1978

Space and time resolved emission of hard X-rays from a plasma focus

The X-ray emission from focused plasmas was observed with an image converter camera in the streak and framing modes. Use of a very high gain image intensifier enabled weak hard X-ray emission (above 25 keV) to be recorded. The use of an admixture of higher atomic number into the deuterium was avoided, and the role of the vapor from the anode surface could be discerned. The recorded bremsstrahlung emission seemed to be from a metallic plasma of copper released from the anode surface by bombardment from an intense electron beam. The intensity of emission was determined by the density of copper and the density and energy of the electron beam. The main emission recorded occurred several 100 nsec after the focus was over, which implies that the electric fields driving the beam existed for this duration. It is suggested that the fields were created by annihilation of magnetic flux for a time much longer than the focus duration.

Harries, W. L.↗
NASA NTRS2011

Miniature, low-power X-ray tube using a microchannel electron generator electron source

Embodiments of the invention provide a novel, low-power X-ray tube and X-ray generating system. Embodiments of the invention use a multichannel electron generator as the electron source, thereby increasing reliability and decreasing power consumption of the X-ray tube. Unlike tubes using a conventional filament that must be heated by a current power source, embodiments of the invention require only a voltage power source, use very little current, and have no cooling requirements. The microchannel electron generator comprises one or more microchannel plates (MCPs), Each MCP comprises a honeycomb assembly of a plurality of annular components, which may be stacked to increase electron intensity. The multichannel electron generator used enables directional control of electron flow. In addition, the multichannel electron generator used is more robust than conventional filaments, making the resulting X-ray tube very shock and vibration resistant.

Elam, Wm. Timothy↗
NASA NTRS1982

Theoretical study of IR band intensities and electronic transition moments for the beta and delta systems of NO

The variation of the electronic transition moment with internuclear separation has been calculated for the beta and delta systems of NO. Theoretical band intensities for the fundamental and first two overtones have also been calculated for the ground state. The results are based on the self-consistent-field plus configuration-interaction technique, and they are compared with the existing experimental data. Theoretical potential-energy curves and the spectroscopic constants for the X-squared Pi, B-squared Pi, and C-squared Pi electronic states of NO are also reported.

Cooper, D. M.↗
NASA NTRS1975

Electron precipitation in the post midnight sector of the auroral zones

Comprehensive measurements of the angular distributions and energy spectra of electron intensities with electrostatic analyzer arrays on board the low-altitude satellite Injun 5 are reported. These are for the post-midnight sector of the auroral zones during the high-intensity events accompanying magnetic substorms. Precipitation features on closed terrestrial field lines well equatorward of the trapping boundary for energetic electrons with E greater than 45 keV were examined. No evidences of maxima in the differential energy spectra or of strongly field-aligned currents which are indicative of quasi-static electric fields aligned parallel to the geomagnetic field were found. Precipitation of low-energy electron intensities fluctuated on time scales greater than 2 seconds as viewed at the satellite position. This precipitation was characterized by isotropy for all pitch angles outside the atmospheric backscatter cone.

Frank, L. A.↗
NASA NTRS1976

Observations of Jovian electrons at 1 AU

It has recently been suggested that electrons of Jovian origin are responsible for the quiet-time increases in the electron intensity greater than 3 MeV observed at 1 AU. Using data from electron/isotope spectrometers on Imp 7 and 8, the temporal behavior of quiet-time electrons at 1 AU is studied over the period October 1972 through May 1975. The 1- to 6-MeV electron intensity is found to vary by a factor of about 10 from one quiet-time period to another, including numerous short-term enhancements characteristic of the quiet-time increases reported during 1964-1972. The magnitude and frequency of the increases grow abruptly and remain high for an approximate 4-month period beginning with the time at which the interplanetary field line first connects earth and Jupiter. It is suggested that the interconnection of the interplanetary field with an extended Jovian magnetotail of about 2 AU in length could result in the observed longitudinal distribution of Jovian electrons of 1 AU.

Mewaldt, R. A.↗
NASA NTRS1973

Metallic Fe phases in Apollo 16 fines - Their origin and characteristics as revealed by electron spin resonance studies

The intense electron spin resonance (ESR) signals detected in the Apollo 16 fines from three sites (61141,4, Station 1; 64501,22, South Ray Crater; 67601,20, North Ray Crater) are found to be essentially similar in g-value, in lineshape asymmetry and in temperature dependence to those previously observed for the Apollo 11-15 fines. On the basis of these similarities, it is concluded that these ESR signals like those detected in the Apollo 11-15 fines are principally ferromagnetic in nature arising from metallic Fe phases having the body-centered cubic structure, and not from hematite, magnetite, or any other ferric oxides. It is shown that a quantitative correlation exists between the ESR linewidth observed for the Apollo 11-16 fines and their average Ni contents in the metallic Fe phases as determined by other means. A common source of meteoritic origin is indicated for the metallic Fe phases of these samples.

Tsay, F.-D.↗
NASA NTRS1971

Local-time survey of plasma at low altitudes over the auroral zones

A local-time survey of the low energy proton and electron intensities precipitated into the earth's atmosphere during periods of magnetic quiescence was constructed. A typical, individual satellite crossing of this region in each of eight local-time sectors was selected from a library of similar observations with the polar-orbiting satellite Injun 5. The trapping boundary for more energetic electron intensities, E 45 keV, is a natural coordinate for delineating the boundary between the two major types of lower energy, 50 or = E or = 15,000 eV. The main contributors to electron energy influx are inverted V precipitation poleward of the trapping boundary and the plasma sheet intensities equatorward. These are interpreted in terms of a magnetospheric model.

Frank, L. A.↗
NASA NTRS1975

Quantitative comparisons of type 3 radio burst intensity and fast electron flux at 1 AU

The flux of fast solar electrons and the intensity of the type 111 radio emission generated by these particles were compared at one AU. Two regimes were found in the generation of type 111 radiation: one where the radio intensity is linearly proportional to the electron flux, and another, which occurs above a threshold electron flux, where the radio intensity is approximately proportional to the 2.4 power of the electron flux. This threshold appears to reflect a transition to a different emission mechanism.

Fitzenreiter, R. J.↗
NASA NTRS1976

Quantitative comparisons of type III radio burst intensity and fast electron flux at 1 AU

We compare the flux of fast solar electrons and the intensity of the type III radio emission generated by these particles at 1 AU. We find that there are two regimes in the generation of type III radiation: one where the radio intensity is linearly proportional to the electron flux, and the second regime, which occurs above a threshold electron flux, where the radio intensity is proportional to the approximately 2.4 power of the electron flux. This threshold appears to reflect a transition to a different emission mechanism.

Fitzenreiter, R. J.↗