Ionospheric modification and parametric instabilities

Fejer, J. A.

doi:10.1029/rg017i001p00135

Cited by 303 publications

(230 citation statements)

References 65 publications

(57 reference statements)

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“…These wave modes give rise to enhancements in both the E-and F-region ion and plasma line incoherent scatter spectra. These spectral enhancements are thought to be caused by excitation of instabilities (Perkins and Kaw, 1971) that include the purely growing mode (Fejer and Leer, 1972), also called the oscillating two-stream instability or modulational instability (Rietveld et al, 2002), and the parametric decay instability (Fejer, 1979). These two instabilities were first observed using the HF heating facility at Arecibo (Carlson et al, 1972;Gordon and Carlson, 1974) as summarized in the review by Carlson and Duncan (1977).…”

Section: Introductionmentioning

confidence: 99%

EISCAT Svalbard radar observations of SPEAR-induced E- and F-region spectral enhancements in the polar cap ionosphere

2007

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Abstract. The Space Plasma Exploration by Active Radar (SPEAR) facility has successfully operated in the high-power heater and low-power radar modes and has returned its first results. The high-power results include observations of SPEAR-induced ion and plasma line spectral enhancements recorded by the EISCAT Svalbard UHF incoherent scatter radar system (ESR), which is collocated with SPEAR. These SPEAR-enhanced spectra possess features that are consistent with excitation of both the purely growing mode and the parametric decay instability. In this paper, we present observations of upper and lower E-region SPEAR-induced ion and plasma line enhancements, together with F-region spectral enhancements, which indicate excitation of both instabilities and which are consistent with previous theoretical treatments of instability excitation in sporadic E-layers. In agreement with previous observations, spectra from the lower Eregion have the single-peaked form characteristic of collisional plasma. Our observations of the SPEAR-enhanced E-region spectra suggest the presence of variable drifting regions of patchy overdense plasma, which is a finding also consistent with previous results.

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Section: Introductionmentioning

confidence: 99%

EISCAT Svalbard radar observations of SPEAR-induced E- and F-region spectral enhancements in the polar cap ionosphere

2007

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“…The beam (À3 dB beam size $8.6°) was pointing into the magnetic zenith with a transmitter long pulse of 998 ms ($150 km), receiver gating of 10 ms ($1.5 km), and a data dump time of 10 ms, which was subsequently integrated for 2 s. Observations were made for 0317 -0339 and 0341-0436 UT. Pumping the ionosphere with powerful HF radio waves results in parametric decay instabilities just below the HF reflection altitude [Fejer, 1979], which produce Langmuir and ionacoustic waves to which MUIR is sensitive in the plasmaline and ion-line channels, respectively. Hence during the pump pulses, the radar can measure the pump wave reflection altitude with high temporal resolution.…”

Section: Introductionmentioning

confidence: 99%

Temporal evolution of pump beam self‐focusing at the High‐Frequency Active Auroral Research Program

et al. 2007

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[1] On 4 February 2005 the High-Frequency Active Auroral Research Program (HAARP) facility was operated at 2.85 MHz to produce artificial optical emissions in the ionosphere while passing through the second electron gyroharmonic. All-sky optical recordings were performed with 15 s integration, alternating between 557.7 and 630 nm. We report the first optical observations showing the temporal evolution of large-scale pump wave selffocusing in the magnetic zenith, observed in the 557.7 nm images. These clearly show that the maximum intensity was not reached after 15 s of pumping, which is unexpected since the emission delay time is <1 s, and that the optical signature had intensified in a much smaller region within the beam after 45 s of pumping. In addition, adjacent regions within the beam lost intensity. Radar measurements indicate a plasma depletion of $1% near the HF reflection altitude. Ray tracing of the pump wave through the plasma depletion region, which forms a concave reflecting radio wave mirror, reproduces the optical spatial morphology. A radio wave flux density gain of up to $30 dB may occur. In addition, the ray trace is consistent with the observed artificial optical emissions for critical plasma frequencies down to $0.5 MHz below the pump frequency.

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“…ia is an ion acoustic wave of a much lower frequency. Langmuir waves have a frequency given by Fejer [1979]:…”

Section: Introductionmentioning

confidence: 99%

The thresholds of ionospheric plasma instabilities pumped by high‐frequency radio waves at EISCAT

et al. 2013

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[1] We test the existing theories regarding the thresholds for the parametric decay instability (PDI), the oscillating two-steam instability (OTSI), and the thermal parametric instability (TPI) using the European Incoherent Scatter (EISCAT) facility's ionospheric heater. In these processes, the pump wave can couple to various electrostatic waves in the F layer ionosphere, which can be observed using the EISCAT UHF radar (PDI and OTSI) or by HF radar (TPI). On 19 October 2012, the heater power was stepped from 0.5 MW to 100 MW effective radiated power in seven steps using a 1 min on, 1 min off cycle. We use an electric field model, taking into account D region absorption, to compare theory with our observations. In all three cases, we find good agreement. In addition, the growth of striations formed during the TPI causes anomalous absorption of the heater wave, which we observe as decreased UHF ion line and plasma line backscatter power. We show evidence that heating for a prolonged period of time reduces the UHF ion line intensity throughout the experiment.Citation: Bryers, C. J., M. J. Kosch, A. Senior, M. T. Rietveld, and T. K. Yeoman (2013), The thresholds of ionospheric plasma instabilities pumped by high-frequency radio waves at EISCAT,

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Ionospheric modification and parametric instabilities

Cited by 303 publications

References 65 publications

EISCAT Svalbard radar observations of SPEAR-induced E- and F-region spectral enhancements in the polar cap ionosphere

EISCAT Svalbard radar observations of SPEAR-induced E- and F-region spectral enhancements in the polar cap ionosphere

Temporal evolution of pump beam self‐focusing at the High‐Frequency Active Auroral Research Program

The thresholds of ionospheric plasma instabilities pumped by high‐frequency radio waves at EISCAT

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