Modifying the Ionosphere with Intense Radio Waves

Utlaut, W. F.; Cohen, Robert

doi:10.1126/science.174.4006.245

Cited by 138 publications

(52 citation statements)

References 18 publications

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“…The ionosphere is also treated as a natural space plasma laboratory and modulated more actively using high-power HF pump waves, so as to study the interactions of the electromagnetic waves and plasma. Research attempts in this area began with the Platteville heating experiments conducted in Colorado, USA, in the 1960s (Utlaut, 1970;Utlaut and Cohen, 1971;Utlaut and Violette, 1972). In ionospheric modification experiments, a powerful HF electromagnetic wave incident on the ionosphere can produce nonlinear effects on time scales ranging from tens of microseconds to minutes, and on size scales ranging from meters to kilometers.…”

Section: Introductionmentioning

confidence: 99%

Analysis and simulation of standing wave pattern of powerful HF radio waves in ionospheric reflection region

et al. 2015

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For the study of the various non-linear effects generated in ionospheric modulation experiments, accurate calculation of the field intensity variation in the whole reflection region for an electromagnetic wave vertically impinging upon the ionosphere is meaningful. In this paper, mathematical expressions of the electric field components of the characteristic heating waves are derived, by coupling the equation describing a wave initially impinging vertically upon the ionosphere with the Forsterling equation. The variation of each component of the electric field and the total electric field intensity of the standing wave pattern under a specific density profile are calculated by means of a uniform approximation, which is applied throughout the region near the reflection point. The numerical calculation results demonstrate that the total electric field intensity of the ordinary (O)-mode wave varies rapidly in space and reaches several maxima below the reflection point. Evident swelling phenomena of the electric field intensity are found. Our results also indicate that this effect is more pronounced at higher latitudes and that the geomagnetic field is important for wave pattern variation. The electric field intensity of the standing wave pattern of the extraordinary (X)-mode wave exhibits some growth below the reflection point, but its swelling effect is significantly weaker than that of the O-mode wave.

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Section: Introductionmentioning

confidence: 99%

Analysis and simulation of standing wave pattern of powerful HF radio waves in ionospheric reflection region

et al. 2015

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“…which are known, I a I is an infinite column vector with elements a., and I PI is an infinite column with elements zero except the central one which is equal to iie. Equation (7) determines all the elements a • and the field is given by Vb r which can be written as (see Fig. 1)…”

Section: General Solutionmentioning

confidence: 99%

“…The space-time periodicity can be considered as due to a strong pump wave. Such a case can be encountered in devices, in the earth ionosphere submitted to high-power radar pulses, 7 planetary ionosphere disturbed by the motion of a large body (like the satellite Io moving in the Jovian atmosphere and the resulting correlation with the Jovian decametric emission), and others.…”

Section: Introductionmentioning

confidence: 99%

Cerenkov and transition radiation in space-time periodic media

Elachi

1972

Journal of Applied Physics

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EFFECTS OF DIELECTRIC CONTAINERS 3719though it could be a necessary correction for techniques employing different geometries. The procedure represented by the application of Eq. (7) corrects for the combined effect of the container wall and the holes in the cavity. Plasma density measurementsThe motivation for the present work was the requirement for accurate electron densities in the positive column of a glow discharge in helium over a range of discharge currents and gas pressures. 8 Using a quartz tube with 0. 4 -mm -thick walls, the resonance frequency shifts t:.fd were first determined for the six dielectric slugs described above. The quartz tube was then made part of the positive column of the helium discharge and the frequency shifts C:.fP were then observed for the desired set of pressures and currents. The integrals gd and gP of Eq. (7) were machine calculated, now using for convenience the theoretical distributions Ei(r) of Eq. (8). Of the set of values of fd, the one chosen in a particular density determination made the ratio t:.f/ C:.fP nearest unity. Equation (7) then yielded the corresponding electron density. The densities obtained were about 16% larger than would have been obtained without the refined calibration procedure described above. Microwave bridge measurementFrequently, plasma densities are measured in a microwave bridge circuit 4 rather than by a frequency shift of a resonator, and the field attenuation and distortions as introduced by the dielectric container walls (plus that of the holes in the waveguides, or of the distorted antenna radiation fields) are sources of errors of the same magnitude as in the above case. For example, it was found that a 1-mm-thick Pyrex tube (same dimensions as above) inserted in an X-band waveguide reduced the measured phase shifts of the dielectric samples by 74%! A quartz tube of the same wall thickness introduced similarly 32% error. Such errors can be avoided by the simple calibration procedure outlined above. CONCLUSIONIt has been shown that plasma containers made from quartz or Pyrex will attenuate microwave fields appreciably and that holes cut into resonance cavities will distort fields, with each effect leading to significant errors in microwave density measurements. However, when proper calibration procedures are employed, such errors can be minimized. It is thus recommended that the calibration procedure described above be followed when large errors in electron density measurements are to be avoided. Chern. Phys. 56, 1077Phys. 56, (1972 J. Chern. Phys. 56, 1411. Cerenkov and transition radiation in space-time periodic media Charles ElachiJet Propulsion Laboratory and California Institute of Technology, Pasadena, California 91109 (Received 17 March 1972) The solution to the problem of determining the radiation emitted by a uniformly moving charged particle in a sinusoidally space-time periodic medium is obtained. The space-time periodicity can be considered as due to a strong pump wave and is expressed as a traveling-wave-type change in th...

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“…Several publications [1][2][3][4][5][6][7][8][9][10][11][12] in this field have appeared in the scientific literature since 1962. Apart from the scientific point of view, the results in this field have a bearing on ionospheric modification experiments, [13][14][15][16][17][18][19] beams from proposed satellite power stations passing through the ionosphere, 20 and laser plasma interaction phenomena.…”

Section: Introductionmentioning

confidence: 99%

Self-focusing instability in ionospheric plasma with thermal conduction

Sodha¹,

Sharma

Verma

et al. 2007

Physics of Plasmas

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In this communication, an expression for the growth rate of self-focusing instability in the ionospheric plasma has been derived after taking finite thermal conduction into account. The instability arises on account of the depletion of electrons from regions where the irradiance of the perturbation is large. In contrast to earlier work, an appropriate energy balance equation for electrons and ions and the proper dependence of thermal conductivity on electron temperature have been used. The dependence of the growth rate of the filamentation instability on the background irradiation, thermal conductivity, and the wave number of transverse perturbation has been investigated. The mid-latitude daytime ionospheric model of Gurevich has been used for numerical computations, corresponding to a height of 200 km. The gradient of irradiance perturbations is assumed to be along the magnetic field of the Earth. The numerical results have been illustrated graphically and discussed.

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Modifying the Ionosphere with Intense Radio Waves

Cited by 138 publications

References 18 publications

Analysis and simulation of standing wave pattern of powerful HF radio waves in ionospheric reflection region

Analysis and simulation of standing wave pattern of powerful HF radio waves in ionospheric reflection region

Cerenkov and transition radiation in space-time periodic media

Self-focusing instability in ionospheric plasma with thermal conduction

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