Evidence for drift waves in ionospheric heating experiments

Kelley, M. C.

doi:10.1029/2004gl020105

Cited by 4 publications

(5 citation statements)

References 17 publications

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“…Theoretical work (Antani and Guzdar, 1999;Borisov, 2004) suggests that drift waves would be excited by the high temperature and density gradients associated with the artificial irregularities. These drift waves have already been suggested as a source of very small-scale fieldtransverse structure observed in in-situ measurements (Kelley et al, 1995;Kelley, 2004), although this is probably too weak to make a significant contribution to HF radar backscatter. The turbulence associated with the drift waves would lead to additional structuring in the plasma along the magnetic field too, thus reducing aspect sensitivity.…”

Section: Tid Effect On Hf Radar Observations Of the Artificial Irregumentioning

confidence: 99%

Effects of high-latitude atmospheric gravity wave disturbances on artificial HF radar backscatter

et al. 2006

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Abstract.Observations of HF radar backscatter from artificial field-aligned irregularities in an ionosphere perturbed by travelling disturbances due to atmospheric gravity waves are presented. Some features of the spatio-temporal structure of the artificial radar backscatter can be explained in terms of the distortion of the ionosphere resulting from the travelling disturbances. The distorted ionosphere can allow the HF pump wave to access upper-hybrid resonance at larger distances from the transmitter than are normally observed and can also prevent the pump wave reaching this resonance at close distances. The variation in altitude of the irregularities sometimes results in a significant variation in the elevation angle of arrival of the backscattered signal at the radar implying that the radar "sees" a target moving in altitude. We suggest that this may be evidence of off-orthogonal scattering from the irregularities.

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Section: Tid Effect On Hf Radar Observations Of the Artificial Irregumentioning

confidence: 99%

Effects of high-latitude atmospheric gravity wave disturbances on artificial HF radar backscatter

et al. 2006

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“…Probably this is the reason why the LH waves were not detected before at oblique sounding in contrast with the UHR oscillations excited directly at the heater frequency. At the same time the results of the rocket experiment [25][26][27] give a hint that LH waves are excited due to the heating. According to Kelley 27 "The indicated wavelengths are so short that the lower hybrid drift mode may be the actual mode generated.…”

Section: Discussionmentioning

confidence: 89%

“…Later on the relative electron temperature enhancement inside striations was estimated 26 and also the excitation of drift waves was confirmed. 27 It is known from the theory that LH waves should be excited artificially in ionospheric modification experiments. 28 Also, it is concluded from the analysis of the experimental data that LH waves are generated in the process of ionospheric heating.…”

Section: Introductionmentioning

confidence: 99%

Excitation and trapping of lower hybrid waves in striations

Borisov

Honary

2008

Physics of Plasmas

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The theory of lower hybrid ͑LH͒ waves trapped in striations in warm ionospheric plasma in the three-dimensional case is presented. A specific mechanism of trapping associated with the linear transformation of waves is discussed. It is shown analytically that such trapping can take place in elongated plasma depletions with the frequencies below and above the lower hybrid resonance frequency of the ambient plasma. The theory is applied mainly to striations generated artificially in ionospheric modification experiments and partly to natural plasma depletions in the auroral upper ionosphere. Typical amplitudes and transverse scales of the trapped LH waves excited in ionospheric modification experiments are estimated. It is shown that such waves possibly can be detected by backscattering at oblique sounding in very high frequency ͑VHF͒ and ultra high frequency ͑UHF͒ ranges.

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“…For λ ⊥ = L /3, ρ i = 5 m, L = 50 m, l = 800 m, and γ = 1.9 s −1 . The only other observation of drift waves in the ionospheric medium occurred during the same rocket flight when 10 m scale, 10% density depletions were detected in the HF beam [ Kelley , 2004].…”

Section: Discussionmentioning

confidence: 99%

Interaction of a high-power UHF beam with the ionosphere

Kelley

Peria

2010

Radio Sci.

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[1] In 1992 a rocket was launched into a high-power radio beam to study its interaction with the ionosphere. The frequency of the beam, 5.1 MHz, was optimized for such interactions since the frequency used was below the maximum plasma frequency and hence was reflected in a manner that optimized such an interaction. Fortuitously, the rocket passed quite close to the diagnostic Arecibo UHF (430 MHz) radar beam and remarkably, as reported here, we find that there was an interaction as well with the UHF beam. In retrospect, however, we see that the energy density of the UHF radar was more than an order of magnitude higher than the plasma energy density. And, although the quiver velocity of the electrons in the beam is only 4% of their thermal speed, the ponderomotive force is quite a bit larger than the other forces in the medium. This force creates a drift velocity perpendicular to the magnetic field at the beam edge which, we show, is unstable to the drift wave instability and is likely to create the heated ions and fluctuating electric field and plasma density we observe. These results suggest that any transmission of high-power radio waves from a solar power satellite to the ground will interact with the ionosphere in a manner that must be studied before such an expensive project is initiated.

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Evidence for drift waves in ionospheric heating experiments

Cited by 4 publications

References 17 publications

Effects of high-latitude atmospheric gravity wave disturbances on artificial HF radar backscatter

Effects of high-latitude atmospheric gravity wave disturbances on artificial HF radar backscatter

Excitation and trapping of lower hybrid waves in striations

Interaction of a high-power UHF beam with the ionosphere

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