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

Bryers, Carl; Kosch, M. J.; Senior, Andrew; Rietveld, M. T.; Yeoman, T. K.

doi:10.1002/2013ja019429

Cited by 31 publications

(59 citation statements)

References 39 publications

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“…It was also shown by Bryers et al . [] that the threshold value of 26 MW was needed to excite the TPI and PDI by an O ‐mode HF pump wave. Despite the fact that leakage of the O mode was small (ERP = 2–5 MW), we cannot completely exclude that it could have an impact on effects during X ‐mode pumping, when the heater frequency was below the critical frequency, f H < f o F 2 .…”

Section: Results From Multiinstrument Observationsmentioning

confidence: 99%

Optical and ionospheric phenomena at EISCAT under continuous X‐mode HF pumping

et al. 2014

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We present experimental results from multiinstrument observations in the high-latitude ionospheric F 2 layer at the EISCAT (European Incoherent Scatter Scientific Association) heating facility. The results come from a set of experiments, when an X-polarized HF pump wave at high heater frequencies (f H > 6.0 MHz) was injected into the F region of the ionosphere toward the magnetic zenith. Experiments were carried out under quiet magnetic conditions with an effective radiated power of 458-548 MW. HF pumping was produced at different heater frequencies, away from electron gyroharmonic frequencies, and different durations of heater pulses. We show the first experimental evidence of the excitation of artificial optical emissions at red (630 nm) and green (557.7 nm) lines in the high-latitude ionospheric F 2 layer induced by an X-polarized HF pump wave. Intensities at red and green lines varied in the range 110-950 R and 50-350 R, respectively, with a ratio of green to red line of 0.35-0.5. The results of optical observations are compared with behaviors of the HF-enhanced ion and plasma lines from EISCAT UHF incoherent scatter radar data and small-scale field-aligned artificial irregularities from Cooperative UK Twin Located Auroral Sounding System observations. It was found that the X-mode radio-induced optical emissions coexisted with HF-enhanced ion and plasma lines and strong artificial field-aligned irregularities throughout the whole heater pulse. It is indicative that parametric decay or oscillating two-stream instabilities were not quenched by fully established small-scale field-aligned artificial irregularities excited by an X-mode HF pump wave.

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Section: Results From Multiinstrument Observationsmentioning

confidence: 99%

Optical and ionospheric phenomena at EISCAT under continuous X‐mode HF pumping

et al. 2014

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“…The intensity of the pump has to exceed the thresholds of the parametric decay instability and the oscillation two‐stream instability, respectively [ Robinson , ; Bryers et al ., :]

E_{normalt normalp} = \sqrt{4 N_{e 0} k_{B} T_{i} ν true/ ((), ε_{0} ω_{p e} B_{\max})}

E_{normalt normalo} = \sqrt{([], 4 ((), 1 + \frac{T_{e}}{T_{i}}) N_{e 0} k_{B} T_{i} ν) true/ ((), ε_{0} ω_{normalp normale})}

to overcome such saturation process as collision, where T i , v , and k B are the ion temperature, electron collision frequency, and the Boltzmann constant, B max a function of T e / T i and with a value of ~0.56 for T e / T i = 2 [ Stubbe et al ., ]. During the experiment focused in this paper, the UHF radar measured T i , T e / T i , and v at the altitude of 200 km are ~1000 K, ~1.95, and ~10 Hz, respectively, then E tp ≈ 0.036 V/m and E to ≈ 0.046 V/m can be obtained.…”

Section: Discussionmentioning

confidence: 99%

The behavior of electron density and temperature during ionospheric heating near the fifth electron gyrofrequency

Rietveld

et al. 2017

JGR Space Physics

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The experimental phenomena involving the changes in electron temperature and electron density as a function of pump frequency during an ionospheric heating campaign at European Incoherent Scatter near Tromsø, Norway, are reported. When the pump frequency is slightly above the fifth electron gyrofrequency, the UHF radar observation shows some apparent enhancements over a wide altitude range in radar echo, ion line, and electron density respectively, which are apparently altitude independent and consistent temporally with the upshifting and spread of plasma line around the reflection altitude. However, they do not, in fact, correspond to true increase in electron density. Based on some existing theories, some discussions are presented to try to explain the above enhancements and the upshifting and spread of plasma line. Even so, the mechanism remains to be determined. In addition, the observation also shows some enhancements in electron temperature as a function of pump frequency around the reflection altitude of the pump, which are dependent on the behavior of dispersion of the upper hybrid wave near the fifth electron gyrofrequency.

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“…The electron density and temperature enhancements depend on the ratio of pump wave frequency to the critical frequency of O-mode HF wave in F 2 layer [Blagoveshchenskaya et al, 2015]. An ordinary polarized electromagnetic wave with about 100 MW ERP can excite the TPI [Bryers et al, 2013], by which upper hybrid waves are excited and the power of pump wave is drained off in the interaction area. In other words, a possible leakage of O-mode wave can excite PDI and OTSI under X-mode pumping in the overdense ionosphere, i.e., f 0 < f o F 2 .…”

Section: 1002/2016ja022411mentioning

confidence: 99%

“…In other words, a possible leakage of O-mode wave can excite PDI and OTSI under X-mode pumping in the overdense ionosphere, i.e., f 0 < f o F 2 . Under X-mode heating wave, the leakage of the O-mode wave is estimated as 2-3% of full ERP; i.e., ERP of the small fraction of O-mode wave is about~10-15 MW, much less than the requirement of TPI threshold reported by Bryers et al [2013]. The experiment with an alternating O/X-mode heating wave was conducted on 19 October 2012 from 17:01 UT to 17:30 UT.…”

Section: 1002/2016ja022411mentioning

confidence: 99%

“…While the pump wave with ordinary polarization (O-mode) has been extensively studied to explain the excitation of parametric instability in the past decades [Perkins et al, 1974;Fejer, 1979;Fejer and Leer, 1972;Kuo, 1996Kuo, , 2002Kuo, , 2015Kuo et al, 1983Kuo et al, , 2014Bryers et al, 2013], the extraordinary polarized (X-mode) pump wave has been considered not to be able to excite Langmuir wave near its reflection height due to the frequency matching condition not being satisfied [Kuo, 2015]. The issue with the excitation of Langmuir parametric decay instability (PDI) and Langmuir oscillating two-stream instability (OTSI) by X-mode heating is due to the fact that the plasma frequency near X-mode pump wave reflection height is less than the heater frequency, thus not satisfying the frequency matching condition.…”

Section: Introductionmentioning

confidence: 99%

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A theoretical investigation on the parametric instability excited by X‐mode polarized electromagnetic wave at Tromsø

et al. 2016

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Recent ionospheric modification experiments performed at Tromsø, Norway, have indicated that X‐mode pump wave is capable of stimulating high‐frequency enhanced plasma lines, which manifests the excitation of parametric instability. This paper investigates theoretically how the observation can be explained by the excitation of parametric instability driven by X‐mode pump wave. The threshold of the parametric instability has been calculated for several recent experimental observations at Tromsø, illustrating that our derived equations for the excitation of parametric instability for X‐mode heating can explain the experimental observations. According to our theoretical calculation, a minimum fraction of pump wave electric field needs to be directed along the geomagnetic field direction in order for the parametric instability threshold to be met. A full‐wave finite difference time domain simulation has been performed to demonstrate that a small parallel component of pump wave electric field can be achieved during X‐mode heating in the presence of inhomogeneous plasma.

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

Cited by 31 publications

References 39 publications

Optical and ionospheric phenomena at EISCAT under continuous X‐mode HF pumping

Optical and ionospheric phenomena at EISCAT under continuous X‐mode HF pumping

The behavior of electron density and temperature during ionospheric heating near the fifth electron gyrofrequency

A theoretical investigation on the parametric instability excited by X‐mode polarized electromagnetic wave at Tromsø

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