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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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At least 37 records · Page 2
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NASA NTRS1975

Electron plasma oscillations associated with type III radio emissions and solar electrons

Results of an extensive search for electron plasma oscillations associated with type III radio noise bursts are presented which were obtained by analyzing 87 type III bursts detected in plasma-wave and charged-particle measurements carried out by IMP 6, 7, and 8. Only one case is found for which plasma oscillations were associated with electrons of solar origin; at least eight events are identified in which no plasma oscillations were detected even though electrons from solar flares were clearly evident. The type III emissions are compared with similar radiation coming from upstream of earth's bow shock at the harmonic of the local electron plasma frequency, and quantitative calculations of the rate of conversion from plasma oscillatory energy to electromagnetic radiation are performed. The results show that electron plasma oscillations are seldom observed in association with solar electron events and type III radio bursts at 1.0 AU and that neither the type III emissions nor the radiation from upstream of the bow shock can be adequately explained by a current model for the coupling of electron plasma oscillations to electromagnetic radiation. Several possible explanations are considered for this discrepancy between theory and observations.

Gurnett, D. A.↗
NASA NTRS2001

Multiplexing of Radio-Frequency Single Electron Transistors

We present results on wavelength division multiplexing of radio-frequency single electron transistors. We use a network of resonant impedance matching circuits to direct applied rf carrier waves to different transistors depending on carrier frequency. A two-channel demonstration of this concept using discrete components successfully reconstructed input signals with small levels of cross coupling. A lithographic version of the rf circuits had measured parameters in agreement with electromagnetic modeling, with reduced cross capacitance and inductance, and should allow 20 to 50 channels to be multiplexed.

Stevenson, Thomas R.↗
NASA NTRS1977

X rays from radio binaries

The radio emission from Beta Persei is interpreted as synchrotron emission, and it is suggested that the observed X-ray emission is due to inverse Compton scattering of light from the primary star by the radio electrons. Annihilation of rotationally twisted magnetic-field lines connecting the binary stars is assumed to be the energy source for the electrons. This model is used to calculate the X-ray emission expected from Beta Persei as well as from the other radio binaries CC Cas, AR Lac, Beta Lyr, b Per, and Cyg X-1. Good agreement between observed and computed fluxes is found for Beta Persei, but the result for Cyg X-1 clearly indicates a different X-ray-emitting process.

Apparao, K. M. V.↗
NASA NTRS1979

HEAO 1 scanning modulation collimator discovery of an extended X-ray source at Cygnus A

The HEAO 1 modulation-collimator data associate the X-ray emission from the Cygnus A region (4U 1957 + 40) with a small area including the radio galaxy. The source appears to be extended, with a size of about 2 arcmin; it may have a complex geometry. Any point-source component must have a flux no greater than 1.3 UFU. A lower limit of 1 microgauss is placed on the magnetic field in the radio lobes, based on the upper limit on the X-ray flux due to inverse Compton scattering of radio electrons on the 2.7-K microwave background radiation. The X-ray emission is more likely due to driven accretion of the intercluster gas onto the giant cD radio galaxy. Therefore this source appears to be similar to the Virgo and Perseus clusters. The density derived for the X-ray-emitting gas is too small for its thermal pressure to confine the radio source.

Fabbiano, G.↗
NASA NTRS2001

Wavelength Division Multiplexing Scheme for Radio-Frequency Single Electron Transistors

We describe work on a wavelength division multiplexing scheme for radio-frequency single electron transistors. We use a network of resonant impedance matching circuits to direct applied rf carrier waves to different transistors depending on carrier frequency. Using discrete components, we made a two-channel demonstration of this concept and successfully reconstructed input signals with small levels of cross coupling. A lithographic version of the rf circuits had measured parameters in agreement with electromagnetic modeling, with reduced cross capacitance and inductance, and should allow 20 to 50 channels to be multiplexed.

Stevenson, Thomas R.↗
NASA NTRS1995

Ulysses-ARTEMIS radio observation of energetic flare electron

Type 3 radio bursts allow us to follow energetic electrons ejected by solar flares into the interplanetary medium, even when the observer is far away from the electrons. The emission frequency f(sub p) is related to the ambient density n(sub e) by f(sub p) varies as the square root of n(sub e), and as a function of the distance r to the sun we have approximately n(sub e) varies as r(exp -2); as a consequence, on a 1/f - t dynamic spectrum type 3 bursts appear as nearly straight traces, whose slope gives an estimation of the source speed. We used the data of the URAP radio receiver on Ulysses (1-1000 kHz), observing sources in the solar wind, and the ground data of the ARTEMIS spectrograph (100-500 MHz), observing sources of the corona, over the years 1991-1994. We found a surprisingly large number of excellent high-frequency - low-frequency associations. A type 3 burst group on ARTEMIS (10 to 100 bursts over 1 to 10 minutes) typically gives rise to one isolated burst on Ulysses. As bursts often start in high frequencies during the maximum phase of flares, this demonstrates in a very convincing manner that some of the flare electrons themselves make it all the way to the interplanetary medium. We discuss decorrelation cases in the context of geometrical configuration between the active region and the two observing sites. We also study how apparent electron speeds vary with the distance to the sun.

Hoang, S.↗
NASA NTRS1974

Monitoring the presence of foreign bodies in the equipment

The methods for monitoring the presence of foreign bodies in radio electronic equipment are discussed. Descriptions of the structural design under the operating principle of the device for detecting foreign bodies weighing to 0.0026 grams are given.

Breslavets, A. V.↗
NASA NTRS1979

Rocket radio measurement of electron density in the nighttime ionosphere

One experimental technique based on the Faraday rotation effect of radio waves is presented for measuring electron density in the nighttime ionosphere at midlatitudes. High frequency linearly-polarized radio signals were transmitted to a linearly-polarized receiving system located in a spinning rocket moving through the ionosphere. Faraday rotation was observed in the reference plane of the rocket as a change in frequency of the detected receiver output. The frequency change was measured and the information was used to obtain electron density data. System performance was evaluated and some sources of error were identified. The data obtained was useful in calibrating a Langmuir probe experiment for electron density values of 100/cu cm and greater. Data from two rocket flights are presented to illustrate the experiment.

Gilchrist, B. E.↗
NASA NTRS1977

Cosmic-ray electrons and galactic radio emission - A conflict

An analysis which takes into account the observed energy spectrum of cosmic-ray electrons above 5 GeV and calculated mean magnetic field data shows that the observed spectral index of the radio continuum in the Galaxy is in conflict with some of the cosmic-ray electron measurements. It is found that the absolute intensities of cosmic-ray electrons measured by some of the experimenters are so low that they cannot be reconciled either with the interstellar magnetic field limits or with the extent of the galactic disk toward the anticenter.

Badhwar, G. D.↗
NASA NTRS1981

Energetic electrons, Type III radio bursts, and impulsive solar flare X-rays

Observations of impulsive hard X-ray and type III radio bursts made during the maximum of the last solar activity cycle are analyzed. Spectral measurements of 10-68 keV X-rays were made with the University of California (Berkeley) experiment aboard the OGO 5 satellite. About 20% of impulsive hard X-ray bursts are correlated with type III radio bursts, whereas only about 3% of the reported type III radio bursts are correlated with impulsive X-ray bursts. The location of the associated H gamma flare on the solar disk has little effect on the X-ray-type III burst correlation. The magnitude of the X-ray-type III burst correlation increases systematically with an increase in the intensity and starting frequency of the radio burst, the peak energy and hardness of the X-ray burst, and the peak nonthermal emission measure and spectral hardness of the electron spectrum not less than 20 keV inside the X-ray source. Observations are consistent with the electron populations responsible for both the X-ray and type III emissions accelerated in a single acceleration process; they also suggest a flare model where the primary instability causing electron acceleration during the impulsive phase occurs in the corona.

Kane, S. R.↗