VLF emissions from a modulated electron beam in the auroral ionosphere

Holzworth, R. H.; Koons, H. C.

doi:10.1029/ja086ia02p00853

Cited by 27 publications

(4 citation statements)

References 5 publications

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“…Holzworth and Koons (1981] noted the detection of emissions at 3 kHz. In experiments on STS-3 [Neupert et al, 1982;Banks et al, 1983 andShawhan et al, 1984] modulation of the beam at 3.1 and 4.8 kHz produced emissions at these frequencies and also at their harmonics up to the maximum observation frequency of 30 kHz.…”

Section: III Radiation From Long Pulse Train Beamsmentioning

confidence: 99%

Radiation from pulsed electron beams in space plasmas

Harker¹,

Banks²

1984

Radio Science

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A theoretical study has been made of the electromagnetic radiation arising from pulsed electron beams. The study assumes an electron beam which has a well‐organized spatial structure determined by a fixed trajectory in a magnetic field and on/off pulsing governed by the electron source. From this model the electromagnetic radiation is determined by adding coherently the radiation from each individual electron in the helical stream. The radiation per unit frequency interval is determined, as well as the radiation per unit solid angle, as a function of both propagation and ray angles, electron beam pulse width and separation, total number of pulses, and beam current. As expected for a coherent process, it is found that the radiated power varies at the square of the beam current. The relatively high efficiency of the beam in producing electromagnetic radiation is illustrated by consideration, among others, of a 1‐keV, 100‐mA beam used in recent experiments on the space shuttle. For these parameters the total radiated power per steradian is calculated at selected angles to be greater than 1% of the total beam power carried as electron kinetic energy. These results provide a useful theoretical basis for planning future electron beam experiments in space plasmas.

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Section: III Radiation From Long Pulse Train Beamsmentioning

confidence: 99%

Radiation from pulsed electron beams in space plasmas

Harker¹,

Banks²

1984

Radio Science

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“…The first modulated beam experiment in the ionosphere [Holzworth and Koons, 1981], injected a 4 kV, 80 mA beam, modulated at 3 kHz. Wave magnetic fields of about 1 mV/m were detected at about 1400 m from the electron accelerator.…”

Section: Since the Inception Of Spaceborne Experiments Considerable mentioning

confidence: 99%

Excitation of VLF waves by an electron beam injected into the ionosphere

Pivovarov¹,

Burke²,

Ride³

et al. 1995

J. Geophys. Res.

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We propose a scenario for radiation of electromagnetic whistlers as a result of the injection of a modulated electron beam into the ionosphere. We show that for plasma parameters typical of the ionosphere and electron beam parameters typical of electron guns carried into space aboard rockets or spacecraft, the interaction can result in the instability of electrostatic waves driven by Cherenkov resonance between the waves and the beam. A linear stability analysis was carried out for two limiting cases: a wide and a narrow electron beam; the wave excitation is shown to develop at typical distances of the order of 1 km. Nonlinear evolution of the instability was investigated by a combination of analytical and numerical methods. Electron beam energy is efficiently transformed into the electrostatic mode. The mechanism of electromagnetic mode generation is then dipole radiation from the electron beam, which is strongly bunched as a result of the electrostatic instability. The efficiency of radiation is a strong function of the ratio of the electron beam velocity to electron Alfven velocity (Vae = C O)ce/O)pe); the possibility of increasing the efficiency of radiation is discussed.

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“…This paper presents new results about the spectrum, intensity, and polarization of electromagnetic wave fields generated by launching a pulsed electron beam into the ionosphere from the space shuttle. Previous experiments with rockets [Cartwright and Kellogg, 1974;Winckler, 1980;Holzworth and Koons, 1981;Winckler et al, 1985] have successfully detected electron beam-produced waves in the VLF and ELF portions of the radio spectrum for brief intervals limited by the rocket trajectory. Earlier measurements by the research groups involved in the present experiments have been made from the shuttle with the OSS-1 mission of STS-3 in March, 1982 [Reeves et al, 1987].…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic fields from pulsed electron beam experiments in space: Spacelab‐2 results

Bush

Reeves

Banks

et al. 1987

Geophysical Research Letters

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During the Spacelab‐2 mission a small satellite carrying various plasma diagnostic instruments was released from the shuttle to co‐orbit at distances up to 300 m. During a magnetic conjunction of the shuttle and the satellite an electron beam modulated at 1.22 kHz was emitted from the shuttle during a 7 min period. The spatial structure of the electromagnetic fields generated by the beam was observed from the satellite out to a distance of 153 m perpendicular to the beam. Electromagnetic radiation at the fundamental and the harmonics of the modulation frequency was observed as well as broad‐banded electrostatic noise. The magnetic field amplitude of the strongest harmonics were comparable to the amplitude of simultaneously observed whistlers, while the electric field amplitudes were estimated to 1–10 mV/m. The observations are related to theories for radiation from pulsed electron beams.

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VLF emissions from a modulated electron beam in the auroral ionosphere

Cited by 27 publications

References 5 publications

Radiation from pulsed electron beams in space plasmas

Radiation from pulsed electron beams in space plasmas

Excitation of VLF waves by an electron beam injected into the ionosphere

Electromagnetic fields from pulsed electron beam experiments in space: Spacelab‐2 results

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