The dependence of F‐region electron heating on HF radio pump power: Measurements at EISCAT Tromsø

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

doi:10.1029/2011ja017267

Cited by 5 publications

(5 citation statements)

References 47 publications

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“…For fluxes below 37.5 μ Wm −2 , corresponding to the lower heater ERP's, the efficiency averages at around 40% whereas the efficiency averages about 70% for the fluxes above the threshold. This is consistent with Senior et al [2012]. This shows that the plasma heating mechanism is boosted from ohmic heating by electromagnetic waves to ohmic heating by electromagnetic and electrostatic UH waves and the efficiency increases.…”

Section: Resultssupporting

confidence: 90%

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EISCAT observations of pump‐enhanced plasma temperature and optical emission excitation rate as a function of power flux

et al. 2012

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[1] We analyze optical emissions and enhanced electron temperatures induced by high power HF radio waves as a function of power flux using the EISCAT heater with a range of effective radiated powers. The UHF radar was used to measure the electron temperatures and densities. The Digital All Sky Imager was used to record the 630.0 nm optical emission intensities. We quantify the HF flux loss due to self-absorption in the D-region (typically 3-11 dB) and refraction in the F-region to determine the flux which reaches the upper-hybrid resonance height. We find a quasi-linear relationship between the HF flux and both the temperature enhancement and the optical emission excitation rate with a threshold at $37.5 mWm À2 . On average $70% of the HF flux at the upper-hybrid resonance height goes in to heating the electrons for fluxes above the threshold compared to $40% for fluxes below the threshold.Citation: Bryers, C. J., M. J. Kosch, A. Senior, M. T. Rietveld, and T. K. Yeoman (2012), EISCAT observations of pumpenhanced plasma temperature and optical emission excitation rate as a function of power flux,

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Section: Resultssupporting

confidence: 90%

“…We follow the procedure of Senior et al [2012] to solve for the heater contribution of the heat source, Q HF . The altitude dependent heat source from the pump wave was approximated by a Gaussian form:

Q_{italicHF} = \frac{1}{w \sqrt{2 π}} J \exp (\frac{- {(z - z_{0})}^{2}}{2 w^{2}})

where J , z 0 and w are constants to be determined.…”

Section: Modelingmentioning

confidence: 99%

EISCAT observations of pump‐enhanced plasma temperature and optical emission excitation rate as a function of power flux

et al. 2012

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“…The electron heating rate Q HF (z, t) due to the HF pumping is modeled by a one-dimensional and asymmetric gaussian along the geomagnetic field. Q HF (z, t) has its maximum Q m at range z 0 and has independent upper (σ u ) and lower (σ d ) half-widths (Senior et al, 2012;Bryers et al, 2013):…”

Section: Electron Heating Modelmentioning

confidence: 99%

Electron heating by HF-pumping of high-latitude ionospheric F-region plasma near magnetic zenith

Leyser¹,

Gustavsson²,

Rexer³

et al. 2019

Preprint

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Abstract. High frequency electromagnetic pumping of ionospheric F-region plasma at high and mid latitudes gives the strongest plasma response in magnetic zenith, antiparallel to the geomagnetic field in the northern hemisphere. This has been observed in optical emissions from the pumped plasma turbulence, electron temperature enhancements, filamentary magnetic field-aligned plasma density irregularities, and in self-focusing of the pump beam in magnetic zenith. We present results of EISCAT (European Incoherent SCATter association) Heating-induced magnetic-zenith effects observed with the EISCAT UHF incoherent scatter radar. With Heating transmitting a left-handed circularly polarised pump beam towards magnetic zenith, the UHF radar was scanned in elevation in steps of 1.0° and 1.5° around magnetic zenith. The electron energy equation was integrated to model the electron temperature and associated electron heating rate and optimized to fit the plasma parameter values measured with the radar. The experimental and modeling results are consistent with pump wave propagation in the L mode in magnetic zenith, rather than in the O mode.

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“…When powerful high‐frequency (HF) radio waves reach the ionosphere, several wave‐plasma interactions are excited and most of the HF wave energy is dissipated by the plasma (Senior et al, ), inducing observable phenomena, such as electron temperature enhancements (Honary et al, ; Rietveld et al, ; Robinson, ), production of electron density striations (Milikh et al, ), artificial ionization (Bernhardt et al, ; Pedersen et al, ), stimulated electromagnetic emissions (Leyser, ), and enhancement of optical emissions (Brändström et al, ; Gustavsson et al, ). At auroral latitudes, it is postulated that incident ordinary mode HF radio waves excite upper‐hybrid (Kosch et al, ), lower‐hybrid (Djuth et al, ), and Langmuir turbulences (Djuth et al, ) as well as electron Bernstein waves (Stubbe et al, ) within magnetic field‐aligned plasma striations in the ionosphere.…”

Section: Introductionmentioning

confidence: 99%

“…The striations will expand from a few meters to hundreds of meters during the first 10–30 s after heating onset before stabilizing, the expansion is primarily in the plane perpendicular to the magnetic field (Coster et al, ; Milikh et al, ). After that point, close to 100% of the HF wave energy is dissipated by the plasma within the interaction region, provided that the pump power flux exceeds 30 μW/m 2 (Senior et al, ).…”

Section: Introductionmentioning

confidence: 99%

The 3‐D Distribution of Artificial Aurora Induced by HF Radio Waves in the Ionosphere

et al. 2019

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We present 3-D excitation rate estimates of artificial aurora in the ionospheric F layer, induced by high-frequency radio waves from the European Incoherent Scatter heating facility. Simultaneous imaging of the artificial aurora was done with four separate Auroral Large Imaging System stations, permitting tomography-like 3-D auroral reconstruction of the enhanced atomic oxygen emissions at 6,300, 5,577, and 8,446 Å. Inspection of the 3-D reconstructions suggests that the distribution of energized electrons is less extended in altitude than predicted by transport calculations of electrons accelerated to 2-100 eV. A possible reason for this discrepancy is that high-frequency pumping might induce an anisotropic distribution of energized electrons.Plain Language Summary Auroral lights can be artificially generated by transmitting high-frequency radio waves with high power into the upper atmosphere. In this article, we use multiple viewpoint imaging of artificially produced aurora to estimate the 3-D distribution of the auroral lights by employing tomography-like techniques. The 3-D distribution is estimated in the red, green, and infrared auroral emission lines with wavelengths of 630.0, 557.7, and 844.6 nm, respectively. These emissions are excited by energetic electrons, which have been accelerated through interaction processes between the transmitted radio waves and plasma in the upper atmosphere, at an altitude of about 220-250 km. We observe that the estimated 3-D auroral distributions are less extended in altitude than indicated by previous theoretical work. A possible reason for this disagreement is that the radio wave-plasma interaction processes might lead to a direction dependent electron acceleration.

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The dependence of F‐region electron heating on HF radio pump power: Measurements at EISCAT Tromsø

Cited by 5 publications

References 47 publications

EISCAT observations of pump‐enhanced plasma temperature and optical emission excitation rate as a function of power flux

EISCAT observations of pump‐enhanced plasma temperature and optical emission excitation rate as a function of power flux

Electron heating by HF-pumping of high-latitude ionospheric F-region plasma near magnetic zenith

The 3‐D Distribution of Artificial Aurora Induced by HF Radio Waves in the Ionosphere

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