共查询到20条相似文献,搜索用时 125 毫秒
1.
We report on the results of studying the lower ionosphere by a method based on the resonant scattering of radio waves by artificial
periodic inhomogeneities of the ionospheric plasma. Different aspects of studying the sporadic E layer such as the influence of the vertical transfer on its formation, the possibility of examination of its ion composition,
and the influence of the ionosphere heating on the layer characteristics are discussed. The results of determining the parameters
of the E
s layer and some characteristics of the lower ionosphere during the creation of artificial periodic inhomogeneities at two
frequencies are presented.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 11, pp. 956–969, November 2008. 相似文献
2.
We present the results of new studies of the sporadic E layer in the case of heating of the ionosphere by high-power HF radio
emission. The measurements were performed at the “Sura” heating facility. Ionosphere was modified by high-power radio emission
from the “Sura” facility and was sounded by the probing radio waves of the same frequency and mode. The heating of the ionosphere
resulted in the formation of artificial periodic inhomogeneities, and an increase in the intensity of all signals scattered
by the D, E, and F regions and the sporadic E layer by 5–20 dB was observed. The increase was observed during heating of the
ionosphere by each magnetoionic component, but was smaller for heating by an ordinary-mode wave. This effect was resonant
and disappeared as a result of the frequency detuning down to 85 kHz. During the ionospheric modification, the signal-intensity
increased due to modulation of the natural profile of the electron number density by the artificial periodic structure.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 8, pp. 695–708, August 2007. 相似文献
3.
G. N. Boiko S. M. Grach E. N. Sergeev G. P. Komrakov N. A. Mityakov K. Groves 《Radiophysics and Quantum Electronics》1999,42(7):601-608
On October 24, 1997, from 16:00 to 19:30 LT, during experiments on the artificial mofification of ionosphere by powerful HF
radiation using spaced heating, we recorded twice a significant (tens of percent) decrease of the electron number density
in the F-layer, synchronous with the operation of the heating trnasmitters. The critical frequency of this layer decreased
by 10–20%. This points to the possibility of artificial generation of large-scale inhomogeneities of the ionospheric plasma
density using spatially split heating.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 7, pp. 682–690, January 1999. 相似文献
4.
A. V. Tolmacheva N. V. Bakhmet’eva V. D. Vyakhirev V. N. Bubukina E. E. Kalinina 《Radiophysics and Quantum Electronics》2011,54(6):365-375
We present the results of measuring the electron number density in the ionospheric E layer by a method based on the creation of artificial periodic irregularities of the ionospheric plasma with two different
spatial scales. Artificial periodic irregularities were created by the radiation of the Sura heating facility at frequencies
4.7 and 5.6 MHz. The electron number density was determined by the ratio of relaxation times of the signals backscattered
by artificial periodic irregularities during their sounding by probing radio waves at the mentioned frequencies. Features
of the electron-density profiles obtained in 2006 and 2007 in the altitude range 95–115 km are discussed and their altitude–time
variations are analyzed. 相似文献
5.
V. V. Belikovich N. V. Bakhmet’eva V. N. Bubukina V. D. Vyakhirev E. E. Kalinina G. P. Komrakov A. V. Tolmacheva 《Radiophysics and Quantum Electronics》2008,51(6):431-437
We present the first results of determining the electron number density in the ionospheric E region by a novel technique based on the creation of artificial periodic irregularities when the ionosphere is affected by
powerful radio emission at two frequencies. Using the results of the measurements performed in October 2006 during heating
of the ionosphere by the “Sura” facility radiation at frequencies 4.7 and 5.6 MHz, we obtained the electron number density
profiles in an altitude range of 100 to 110 km. Features of the procedure of measurement and calculation of the electron number
density are described in detail. It is shown that the method can be used for a study of the irregular structure of the lower
ionosphere.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 6, pp. 477–484, June 2008. 相似文献
6.
V. L. Frolov D. I. Nedzvetsky V. P. Uryadov V. A. Ivanov D. V. Ivanov A. R. Lashchevsky N. V. Ryabova 《Radiophysics and Quantum Electronics》2008,51(5):331-338
We present the results of studying the properties of artificial F-spread that appears on ionograms during heating of the ionospheric
F2 region by a high-power O-mode radio wave. It is shown that the regions of resonant interaction of a high-power radio wave
with plasma, where the pump-wave energy is almost totally absorbed and the plasma is subject to intense heating, affect significantly
the development of a self-focusing instability of a high-power radio wave and the generation of middle-scale (with characteristic
scales across the magnetic field l⊥ ≈ 0.4–1.5 km) artifical ionospheric inhomogeneities. It is established that the intensity of such inhomogeneities depends
on the sign and magnitude of detuning of the pump-wave frequency with respect to the electron gyroresonance harmonic frequency
Δf = fPW − nfce and has the minimum value for Δf ≈ −20 kHz, thus demonstrating the asymmetry of the gyroharmonic properties of their excitation
mechanism. Relationship between the observed phenomena and known characteristics of the artificial ionospheric turbulence
for fPW ≈ nfce is analyzed.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 5, pp. 367–375, May 2008. 相似文献
7.
V. A. Alimov F. I. Vybornov L. M. Erukhimov G. P. Komrakov N. A. Mityakov A. V. Rakhlin 《Radiophysics and Quantum Electronics》1997,40(6):456-458
We show some results of experiments on synchronous sounding of the ionosphere by short-wave signals at the Radiophysical Research
Institute’s test site in Zimenki and Vasil’sursk, Nizhniy Novgorod province, during ionospheric modification by high-power
short radiowaves from transmitters of the “Sura” facility in Vasil’sursk. In the course of experiments we proved directly
the decisive role of large-scale inhomogeneities of the ionospheric plasma with dimensions of from several kilometers to several
dozens of kilometers in the formation of artificial F- spread. The small-scale inhomogeneities with dimensions smaller than
1 km, which are localized in a relatively thin layer near the reflection level of a high-power short radiowave, emerged only
at sounding waves, propagating (reflected) in the immediate vicinity of the center of the heating region.
Radiophysical Research Institute, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika,
Vol. 40, No. 6, pp. 688–692, June, 1997. 相似文献
8.
N. V. Bakhmet’eva V. V. Belikovich M. N. Egereva A. V. Tolmacheva 《Radiophysics and Quantum Electronics》2010,53(2):69-81
We present new results of studying the artificial periodic irregularities produced in the ionosphere by the radio emission
of the high-power heating facility “Sura” during the period of observations of the sporadic E layer. Basing on the measurement results for the velocity of the vertical plasma motion and the electron profile density
in the E region of the ionosphere, which were obtained by the method of resonance scattering of radiowaves by an artificially produced
periodic structure, we analyze the possibility to produce a sporadic E layer by driving metal ions affected by the vertical shear of the velocity, which occurs at these altitudes due to the propagation
of internal gravity waves. The parameters of these waves are evaluated, as well as the mass and concentration of metal ions
in the sporadic E layer. 相似文献
9.
V. A. Alimov F. I.Vybornov E. N. Myasnikov A. V. Rakhlin V. L. Frolov 《Radiophysics and Quantum Electronics》2009,52(9):609-617
We present the results of the experiment on studying the multifractal structure (with inhomogeneity sizes from tens to hundreds
of meters across the Earth’s magnetic field) of the artificial ionospheric turbulence when the midlatitude ionosphere is affected
by high-power HF radio waves. The experimental studies were performed on the basis of the “Sura” heating facility with the
help of radio sounding of the disturbed region of the ionospheric plasma by signals from the Earth’s orbital satellites. The
influence of the magnetic zenith effect on measured multifractal characteristics of the small-scale artificial turbulence
of the midlatitude ionosphere was examined. In the case of vertical radio sounding of the disturbed ionosphere region, the
measured multipower and generalized multifractal spectra of turbulence coincide well with similar multifractal characteristics
of the ionospheric turbulence under natural conditions. This result is explained by the fact that the scattering of signals
by weak quasi-isotropic small-scale inhomogeneities of the electron number density in a thick layer with a typical size of
several hundred kilometers above the region of reflection of high-power HF radio waves gives the major contribution to the
observed amplitude fluctuations of received signals. In the case of oblique sounding of the disturbance region at small angles
between the line of sight to the satellite and the direction of the Earth’s magnetic field, the nonuniform structure of the
small-scale turbulence with a relatively narrow multipower spectrum and small variations in the generalized multifractal spectrum
of the electron number density was detected. Such a fairly well ordered structure of the turbulence is explained by the influence
of the magnetic zenith effect on the generation of anisotropic small-scale artificial turbulence in a thin layer having a
typical size of several ten kilometers and located below the pump-wave reflection height in the upper ionosphere. 相似文献
10.
S. S. Matyugov O. I. Yakovlev V. A. Anufriev 《Radiophysics and Quantum Electronics》2008,51(3):161-169
We analyze characteristics of sporadic layers in the equatorial ionosphere using the results of radio occultation sounding
on the paths between GPS satellites and the CHAMP low-orbiting satellite during the solar flare in October–November 2003.
Variations in the amplitude and phase of signals during the lower-ionosphere sounding are studied. It is shown that the use
of amplitude and phase data allows one to obtain parameters of the sporadic ionospheric structures. The data on the occurrence
frequency, height, thickness, and intensity of the Es layers in the daytime and nighttime equatorial ionosphere are presented.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 3, pp. 181–190, March 2008. 相似文献
11.
N. F. Blagoveshchenskaya T. D. Borisova V. A. Kornienko A. S. Janzhura A. S. Kalishin T. R. Robinson T. K. Yeoman D. M. Wright L. J. Baddeley 《Radiophysics and Quantum Electronics》2008,51(11):847-857
We present the results of experimental studies of specific features in the behavior of small-scale artificial field-aligned
irregularities (AFAIs) and the DM component in the spectra of stimulated electromagnetic emission (SEE). Analysis of experimental
data shows that AFAIs in the polar ionosphere are generated under different background geophysical conditions (season, local
time, the presence of sporadic layers in the E region, etc.). It is shown that AFAIs can be excited not only in the F region, but also in “thick” sporadic E
s layers of the polar ionosphere. The AFAIs were observed in some cycles of heating when the HF heater frequency exceeded the
critical frequency by 0.3–0.5 MHz. Propagation paths of diagnostic HF radio waves scattered by AFAIs were modelled for geophysical
conditions prevailing during the SPEAR heating experiments. Two components, namely, a narrow-banded one with a Doppler-spectrum
width of up to 2 Hz and a broadband one observed in a band of up to 20 Hz, were found in the sporadic E
s layer during the AFAI excitation. Analysis of the SEE spectra shows that the behavior of the DM component in time is irregular,
which is possibly due to strong variations in the critical frequency of the F
2 layer from 3.5 to 4.6 MHz. An interesting feature observed in the SPEAR heating experiments is that the generation of the
DM component was similar to the excitation of AFAIs when the heater frequency was up to 0.5 MHz higher than the critical frequency.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 11, pp. 939–950, November 2008. 相似文献
12.
A. A. Ponyatov V. P. Uryadov V. A. Ivanov D. V. Ivanov A. G. Chernov V. V. Shumaev Yu. N. Cherkashin 《Radiophysics and Quantum Electronics》1999,42(4):269-277
We present the results of experimental studies of the influence of artificial ionospheric disturbances on HF signals used
for oblique sounding of the disturbed volume. The measurements have been performed by a chirp ionosonde over the path Yoshkar-Ola-“Sura”-niznhy
Novgorod with length 234 km. We found the 2F2 mode to disappear (attenuation up to 20 dB) when the ionosphere is influenced
by a vertical powerful radiation in the ordinary mode with long (15 min each) heating and pause intervals. Modeling of the
observed effect was carried out. The calculations agree well with experimental data if the traveling ionospheric disturbances
(TID) with vertical and horizontal scales lz∼20 km and lx∼50 km, respectively, and the relative disturbance of the electron density δN∼0.2–0.3 are amplified (generated) during the
ionosphere heating.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 4, pp. 303–313, April 1999. 相似文献
13.
O. M. Barkhatova A. S. Smirnova R. I. Ulybina 《Radiophysics and Quantum Electronics》2009,52(2):100-107
The cause-and-effect relation between variations in the critical frequency of the F
2 subauroral ionospheric layer and the key solar-magnetospheric parameters is studied. The features of the dependence of the
critical frequency of the subauroral ionosphere on the value and components of the interplanetary magnetic field, the solar-wind
parameters, the X-ray and ultraviolet radiation intensities, the solar zenith angle, and the intensity of precipitation of
low-energy particles are established. Within the framework of this study, codes allowing one to solve the problems of predicting
the critical frequency of the ionosphere by the method of artificial neural networks has been developed. The neural-network
forecasting experiments reveal the characteristic times of the ionospheric response to magnetospheric disturbancs. The found
optimal architecture of the neural network allows us to predict the time series of the critical frequency of the high-latitude
ionosphere for the interval 0.5–3 h with an accuracy of up to 93%. The obtained linear and nonlinear dependences of the critical
frequency of the ionospheric F
2 layer on the geophysical parameters can be used for developing ionospheric models required for determining the maximum usable
frequency of HF radio communication.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 52, No. 2, pp. 109–117, February 2009. 相似文献
14.
E. D. Tereshchenko R. Yu. Yurik T. K. Yeoman T. R. Robinson 《Radiophysics and Quantum Electronics》2008,51(11):858-861
We present the first results of observations of the stimulated electromagnetic emission (SEE) in the ionosphere modified by
the Space Plasma Exploration by Active Radar (SPEAR) heating facility. Observation of the SEE is the key method of ground-based
diagnostics of the ionospheric plasma disturbances due to high-power HF radiation. The presented results were obtained during
the heating campaign performed at the SPEAR facility in February–March 2007. Prominent SEE special features were observed
in periods in which the critical frequency of the F
2 layer was higher than the pump-wave frequency (4.45 MHz). As an example, such special features as the downshifted maximum
and the broad continuum in the region of negative detunings from the pump-wave frequency are presented. Observations clearly
demonstrate that the ionosphere was efficiently excited by the SPEAR heating facility despite the comparatively low pump-wave
power.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 11, pp. 951–955, November 2008. 相似文献
15.
V. L. Frolov G. G. Vertogradov V. G. Vertogradov 《Radiophysics and Quantum Electronics》2008,51(4):247-258
We analyze variations in characteristics of the diagnostic stimulated electromagnetic emission of the ionosphere in the evening
hours including the times of sunset both on the Earth’s surface at the observation point and in the ionosphere over it. It
is found that an increase in typical times of evolution of the diagnostic emission begins to be recorded just before the sunset
on the Earth’s surface when the ionosphere is illuminated and its parameters are not significantly changed yet. We state that
the typical times of evolution of the diagnostic emission increase when the pump-wave frequency approaches the critical frequency
of the ionospheric F2 layer, but such an effect is not as significant as when passing from the illuminated to the unilluminated ionosphere. It
is established that at the stage of diagnostic sounding the pump-wave pulse power does not exert any notable influence on
the first (fast) stage of relaxation of small-scale artificial ionospheric irregularities, but can increase the decay time
of the irregularities at the second (slow) stage of relaxation. Capabilities of the method for a study of artificial plasma
turbulence using the diagnostic stimulated electromagnetic emission are discussed.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 4, pp. 273–286, April 2008. 相似文献
16.
L. E. Kurina 《Radiophysics and Quantum Electronics》1998,41(2):136-142
We study the dynamics of thermodiffusional redistribution of magnetized plasma during local heating of electrons by the field
from an HF electromagnetic source. The characteristic regimes of thermodiffusional formation of finite-sized artificial plasma
inhomogeneities are analyzed in relation to the Earth’s ionospheric conditions. Results of numerical calculations illustrating
features of the dynamics of thermodiffusional redistribution of ionospheric plasma at different altitudes are presented.
N. I. Lobachevsky State University, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika,
Vol. 41, No. 2, pp. 212–221, February, 1998. 相似文献
17.
We present the results of studies of the multifractal structure of slow (of duration τ ≈ 10 s) fluctuations of the received-signal
amplitudes in special experiments on radio-raying of the midlatitude ionosphere by signals from orbital satellites in 2004–2006.
It is shown, in particular, that the method of multifractal analysis of amplitude records of the received signals yields information
on the spectrum of large-scale ionospheric inhomogeneities, which is inaccessible for the classical method of radio scintillations.
From the results of measurements with the use of multifractal processing of experimental data, we found that large-scale (tens
of kilometers) quasiregular electron-density inhomogeneities of traveling ionospheric disturbances (TIDs) have a power-law
spectrum. It is exactly the power-law form of the spatial spectrum of large-scale inhomogeneities of TIDs that can be the
reason for the observed multifractal structure of the intermittency of slow fluctuations of the received-signal amplitudes.
However, under conditions of a developed small-scale turbulence of TIDs, the observed multifractal structure of the received
signals is, as a rule, stipulated by the spatial inhomogeneity of the variance of the integral electron-density fluctuations
of small-scale inhomogeneities on scales comparable with the sizes of large-scale inhomogeneities of TIDs.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 3, pp. 191–198, March 2008. 相似文献
18.
We present the results of the studies of fractal properties of the small-scale inhomogeneities of traveling ionospheric disturbances
in special experiments on radio-raying of the midlatitude ionosphere by signals from orbital satellites in 2004–2006. Along
with the conventional correlation processing of the received signals, we performed their multifractal analysis, as well as
fractal processing of signals by the correlation-integral method. Important information on fractal properties of the small-scale
turbulence for the least studied part of the upper-ionosphere inhomogeneity spectrum in the interval of characteristic scales
l ≈ 1–10 km is obtained. In particular, it is noted that the fractal structure of these inhomogeneities can be originated
from the nonlinear “destruction” of several large-scale sinusoidal structures in a quasistable traveling disturbance. It is
also noted that the multifractal spectra of amplitude fluctuations of the received signals obtained in the experiments in
different years, in different time of the day, and in different seasons of the observations are quite similar. This is evidence
that intermittency is a universal property of the plasma turbulence, at least for the midlatitude upper ionosphere.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 1, pp. 22–30, January 2008. 相似文献
19.
N. V. Bakhmet’eva G. I. Grigor’ev A. V. Tolmacheva 《Radiophysics and Quantum Electronics》2011,53(11):623-637
We present the results of measuring characteristics of the ionosphere and neutral atmosphere by the method of resonant scattering
of radio waves by artificial periodic irregularities of the ionospheric plasma in the altitude range 90–120 km. It is shown
that the altitude–time variations of the measured characteristics are in many respects stipulated by the propagation of atmospheric
waves. Hydrodynamic instabilities in the mesosphere—lower thermosphere are analyzed. Criteria of development of different-type
instabilities are presented. Contribution of different processes to the dynamics of the medium is estimated on the basis of
the measurement results. 相似文献
20.
N. V. Bakhmet’eva V. V. Belikovich Yu. A. Ignat’ev A. A. Ponyatov 《Radiophysics and Quantum Electronics》1999,42(1):22-30
We propose a calculation technique for the main characteristics of a sporadic E-layer, including the effective recombination
coefficient, the relative content of meteor and atmospheric ions in the layer, and the time of its evolution. This technique
is based on measurements of vertical plasma velocities by the method of resonance scattering of radio waves by artificial
periodic inhomogeneities of the electron density. The contribution of internal gravity waves and turbulent motions to the
formation of sporadic layers is estimated. The characteristic values of the turbulent velocity measured by this method at
the heights of the turbopause are presented. The possible mechanisms of mid-latitude sporadic E-layer formation at heights
of 90 to 120 km are considered. Experimental studies confirmed the main statements of the wind shear theory concerning the
determining role of the redistribution of ionization under the action of atmospheric winds with vertical gradient of velocity
in the formation of Es.
Deceased.
Radiophysical Research Institute, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika,
Vol. 42, No. 1, pp. 26–35, January, 1999. 相似文献