Parametric interaction between electromagnetic radiation and ionospheric plasma

Грач, С. М.; Karashtin, A. N.; Mityakov, N. A.; Rapoport, V. O.; Trakhtengerts, V. Yu.

doi:10.1007/bf01037725

Cited by 87 publications

(79 citation statements)

References 1 publication

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“…It was found that kilometer scale patches contained 15-m scale filaments associated with deep density depletions and that the filaments were bunched at 50-500 m scales. In contrast to the kilometer and subkilometer scale irregularities, as discussed in the previous paragraph, the small-scale (meters to tens of meters) irregularities have been attributed to the thermal parametric instability [Grach et al, 1978;Das and Fejer, 1979;Inhester et al, 1981;Gurevich et al, 1995] or the parametric decay of the heater wave to frequencies near the ion cyclotron frequency [Keskinen eta!., 1995]. Although the short wavelength end of the self-focusing instability (many tens of meters) remain adjacent to the medium scale irregularities, the growth times of these two classes of irregularities are very different.…”

Section: Introductionmentioning

confidence: 89%

Evolution of subkilometer scale ionospheric irregularities generated by high‐power HF waves

Basu¹,

Costa²,

Livingston³

et al. 1997

J. Geophys. Res.

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Abstract. Electron density irregularities in the F region excited by the European incoherent scatter (EISCAT) high-power high-frequency (HF) facility in Ramfjordmoen, Norway, have been studied in detail by observing scintillations of 250-MHz satellite signals traversing the HF beam. Spaced antenna measurements were performed to determine the temporal structure of scintillation and the drift of the irregularities. Studies of scintillation spectra indicate that even though the onset occurs nearly simultaneously for all irregularity scale sizes, the electron density irregularities with wavelengths in the range of 50-15 m attain their saturation amplitudes within tens of seconds, whereas longer scale-size irregularities with wavelengths exceeding 100 m saturate in the timescale of minutes. The threshold power density requirement for the generation of irregularities of different scales has also been studied by the variation of the heater power. It is found that for large-scale (>100 m) irregularities the threshold power density varies inversely as the irregularity wavelength with a power law index of 4 as predicted by the theories of self-focusing instability.

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Section: Introductionmentioning

confidence: 89%

Evolution of subkilometer scale ionospheric irregularities generated by high‐power HF waves

Basu¹,

Costa²,

Livingston³

et al. 1997

J. Geophys. Res.

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“…Artificial FAIs are generally believed to be generated by thermal parametric instabilities (TPIs) which form at altitudes slightly above the upper hybrid resonance height where the pump frequency is the Pythagorean sum of the plasma frequency and the electron gyrofrequency (Grach et al, 1977;Das and Fejer, 1979;Grach et al, 1981;Dsythe et al, 1982;Dsythe et al, 1983). In the nonlinear stage of evolution, the TPI goes over to the resonance instability developed by Gurevich (1975, 1977) and expanded upon by Inhester (1982).…”

Section: Discussionmentioning

confidence: 99%

30 MHz radar observations of artificial E region field-aligned plasma irregularities

Hysell

2008

Ann. Geophys.

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Abstract. Artificial E region field aligned irregularities (FAIs) have been observed during heating experiments at the HAARP facility using a new 30 MHz coherent scatter radar imager deployed near Homer, Alaska. Irregularities were observed during brief experiments on three quiet days in July and August, 2007, when the daytime E region critical frequency was close to 3 MHz. Irregularities were consistently generated and detected during experiments with O-mode HF pumping on zenith with a 1-min on, 1-min off CW modulation. The scattering cross sections, rise, and fall times of the echoes were observed as well as their spectral properties. Results were found to be mainly in agreement with observations from other mid-and high-latitude sites with some discrepancies. Radar images of the irregularity-filled volume on one case exhibited clear variations in backscatter power and Doppler shift across the volume. The images furthermore show the emergence of a small irregularity-filled region to the south southwest of the main region in the approximate direction of magnetic zenith.

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“…The threshold pump field amplitude needed for irregularity generation was estimated experimentally by Djuth et al (1985). Excitation thresholds for the thermal oscillating two-stream instability, which is thought to initiate the resonance instability, were predicted by Grach et al (1977), Das and Fejer (1979), and Dysthe et al (1983). Grach et al (1978) and Dysthe et al (1982) also anticipated a hysteresis effect associated with the resonance instability and wave trapping, such that irregularities can be maintained by pump waves with amplitudes below their excitation threshold.…”

Section: Introductionmentioning

confidence: 99%

Radar observations of artificial E-region field-aligned irregularities

et al. 2009

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Abstract. Artificial E region field aligned plasma density irregularities (FAIs) were generated using HAARP in four different experimental modes and observed with a coherent scatter radar imager located 450 km to the southwest where it could detect field-aligned backscatter. The experiments were conducted in July of 2008, during the Polar Aeronomy and Radio Science Summer School (PARS), during quiet conditions in the daytime when the E layer was dense and absorption was modest. The echoes observed during zenith and magnetic zenith heating experiments were deflected from their nominally anticipated horizontal positions toward the midpoint position. The occurrence of hysteresis when heating with amplitude modulated pulses implied the development of the resonance instability, although the threshold for the onset of instability appeared to be higher than what has been predicted theoretically. Heating experiments involving pump frequencies slightly above and below the second electron gyroharmonic frequency produced no significant differences in the observed echoes. Finally, heating with a pump frequency slightly above the E region critical frequency appears to have produced FAIs at two distinct altitudes where the upper-hybrid resonance condition could be satisfied.

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Parametric interaction between electromagnetic radiation and ionospheric plasma

Cited by 87 publications

References 1 publication

Evolution of subkilometer scale ionospheric irregularities generated by high‐power HF waves

Evolution of subkilometer scale ionospheric irregularities generated by high‐power HF waves

30 MHz radar observations of artificial E region field-aligned plasma irregularities

Radar observations of artificial E-region field-aligned irregularities

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