Generation of ELF/ULF waves in the ionosphere by dynamo processes

Papadopoulos, K.; Chang, Chein‐Chi

doi:10.1029/gl012i005p00279

Cited by 33 publications

(14 citation statements)

References 5 publications

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“…Several nonlinear processes have been suggested to produce these low frequency waves. Recent experiments performed at Arecibo ) strongly suggest that mechanisms such asthese proposed by Papadopoulos et al (1983) and Papadopoulos and Chang (1985) are possibly the dominant sources of the ULF waves generated in the ionosphere over Puerto Rico.…”

Section: Utilization Of Ionospheric Antenna In the Elf-hf Bands: Gementioning

confidence: 95%

See 1 more Smart Citation

<title>Effects of high-power RF fields in the atmosphere and the ionosphere</title>

Ganguly

1990

SPIE Proceedings

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Section: Utilization Of Ionospheric Antenna In the Elf-hf Bands: Gementioning

confidence: 95%

“…These could be die to (a) beat wave mechanism (Papadopoulos, et a!, 1982); (b) Dynamo mechanism (Papadopoulos and Chang, 1985); or (c) modulation of the ambient current system.…”

Section: Utilization Of Ionospheric Antenna In the Elf-hf Bands: Gementioning

confidence: 99%

<title>Effects of high-power RF fields in the atmosphere and the ionosphere</title>

Ganguly

1990

SPIE Proceedings

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“…Generation of VLF waves in the high latitude ionosphere via electrojet modulation has been studied experimentally [1][2][3][4][5][6][7][8][9][10][11][12][13] and theoretically. [12][13][14][15][16][17][18][19][20][21][22] The heating and cooling rates as well as the available heating and cooling times in one modulation period affect the efficacy of conductivity modulation by an intensity modulated HF heater. Consequently, the efficacy of VLF generation via electrojet modulation is expected to decrease as the modulation frequency increases.…”

Section: Introductionmentioning

confidence: 99%

Ionospheric very low frequency transmitter

Kuo

2015

Physics of Plasmas

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The theme of this paper is to establish a reliable ionospheric very low frequency (VLF) transmitter, which is also broad band. Two approaches are studied that generate VLF waves in the ionosphere. The first, classic approach employs a ground-based HF heater to directly modulate the high latitude ionospheric, or auroral electrojet. In the classic approach, the intensity-modulated HF heater induces an alternating current in the electrojet, which serves as a virtual antenna to transmit VLF waves. The spatial and temporal variations of the electrojet impact the reliability of the classic approach. The second, beat-wave approach also employs a ground-based HF heater; however, in this approach, the heater operates in a continuous wave mode at two HF frequencies separated by the desired VLF frequency. Theories for both approaches are formulated, calculations performed with numerical model simulations, and the calculations are compared to experimental results. Theory for the classic approach shows that an HF heater wave, intensity-modulated at VLF, modulates the electron temperature dependent electrical conductivity of the ionospheric electrojet, which, in turn, induces an ac electrojet current. Thus, the electrojet becomes a virtual VLF antenna. The numerical results show that the radiation intensity of the modulated electrojet decreases with an increase in VLF radiation frequency. Theory for the beat wave approach shows that the VLF radiation intensity depends upon the HF heater intensity rather than the electrojet strength, and yet this approach can also modulate the electrojet when present. HF heater experiments were conducted for both the intensity modulated and beat wave approaches. VLF radiations were generated and the experimental results confirm the numerical simulations. Theory and experimental results both show that in the absence of the electrojet, VLF radiation from the F-region is generated via the beat wave approach. Additionally, the beat wave approach generates VLF radiations over a larger frequency band than by the modulated electrojet. V C 2015 AIP Publishing LLC.

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“…Thus, the electrojet current in the lower ionosphere can be modulated by the amplitude-modulated HF wave due to the dependence of plasma conductivity on the electron temperature. Generation of ULF/ELF/VLF waves by the modulation current in the electrojet has been studied experimentally [Stubbe, etal., 1981 andStubbe, 1984a, b and1991a, b;Ferraro et al, 1982Ferraro et al, , 1984James, et al, 1984;Lee et al, 1990;McCarrick et al, 1990;Barr et al, 1991] as well as theoretically [Stubbe and Kopka, 1977;Stubbe, etal, 1982;Kuo and Lee, 1983;Papadopoulos and Chang, 1985;Papadopoulos et al, 1990;Kuo and Lee, 1993;Kuo, 1993;Kuo et al, 1998 and2000]. The frequencies of radiation are controlled by the modulation frequency of the amplitudemodulated HF heating wave.…”

Section: Introductionmentioning

confidence: 99%

Summer 2000 Student/Faculty Science Campaign, July 31-August 8, 2000

Snyder¹

2000

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Generation of ELF/ULF waves in the ionosphere by dynamo processes

Cited by 33 publications

References 5 publications

<title>Effects of high-power RF fields in the atmosphere and the ionosphere</title>

<title>Effects of high-power RF fields in the atmosphere and the ionosphere</title>

Ionospheric very low frequency transmitter

Summer 2000 Student/Faculty Science Campaign, July 31-August 8, 2000

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