共查询到20条相似文献,搜索用时 343 毫秒
1.
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
2.
V. V. Belikovich N. V. Bakhmeteva E. E. Kalinina A. V. Tolmacheva 《Radiophysics and Quantum Electronics》2006,49(9):669-674
We propose a new method for determination of the electron number density in the E region of the ionosphere on the basis of
scattering of radio waves from artificial periodic inhomogeneities formed by the high-power radio emission at two frequencies
and having different spatial periods. The ratio of relaxation times of the artificial periodic inhomogeneities at a given
altitude is determined only by the ratio of their spatial periods, which makes it possible to determine electron number density.
The paper presents the corresponding calculations and the estimates of possible measurement errors.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 9, pp. 744–750, September 2006. 相似文献
3.
A. A. Ponyatov V. P. Uryadov V. I. Batukhtin V. A. Ivanov D. V. Ivanov N. V. Ryabova A. G. Chernov V. V. Shumaev S. J. Anderson 《Radiophysics and Quantum Electronics》1999,42(12):999-1006
We present preliminary experimental results concerning transequatorial propagation (TEP) of HF waves upon chirp sounding over
the 11950-km path alice Springs (Australia)-Yoshkar-Ola (Russia). The measurements were made in August, 1998. Two anomalous
signals with delays of 3.0 and 4.5 ms with respect to the main mode were observed during night time (21:30–23:00 UT). The
maximum observed frequencies (MOF) of these signals were 2–3 MHz greater than the main-mode MOF. Simulations allowed us to
identify these signals as the ducted signals trapped in theFE interlayer duct due to radiowave refraction on a negative gradient of the electron density and that escaped from the duct
due to the scattering by small-scale field-aligned irregularities of the subpolar ionosphere. We discuss radiophysical and
geophysical aspects concerning localization of the irregularities responsible for scattering and perspectives of using the
ducted mode for over-the-horizon diagnostics of the inhomogeneous structure of the ionosphere with a global network of chirp
sounders and HF radars.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 12, pp. 1136–1142, December 1999. 相似文献
4.
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
5.
E. D. Tereshchenko A. N. Milichenko V. L. Frolov R. Yu. Yurik 《Radiophysics and Quantum Electronics》2008,51(11):842-846
We present the results of first studies of the modification of the ionosphere by high-power HF radiation, which were obtained
using signals of high-orbit GPS/GLONASS navigation satellites. Enhancement of the ionospheric modification in the magnetic-field
direction was observed for the first time. This leads to a total decrease in electron number density and the formation of
electron density irregularities near the magnetic-zenith direction. The efficiency of using GSP/GLONASS satellite signals
for the studies of the ionosphere modified by HF radiation is demonstrated. Prospects for further studies in this field are
discussed.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 11, pp. 934–938, November 2008. 相似文献
6.
G. G. Vertogradov V. P. Uryadov V. G. Vertogradov 《Radiophysics and Quantum Electronics》2007,50(1):1-7
We present the results of the ionosphere oblique chirp sounding on the Cyprus—Nizhny Novgorod, Cyprus—Rostov-on-Don, and Moscow—Rostov-on-Don
mid-latitude paths during X-ray flares in January 17, 19, and 20, 2005. It is found that during strong flares the blackout
of short radio waves was observed over the entire frequency range of chirp sounding on the Cyprus—Nizhny Novgorod and Cyprus—Rostov-on-Don
paths. Modeling of the electron-density profiles in the lower ionosphere based on absorption of short radio waves on the Moscow—Rostov-on-Don
path at different stages of the decay of the X-ray radiation intensity is carried out. It is shown that at the instant corresponding
to the maximum value of the flare radiation flux, the electron density in the lower ionosphere at altitudes 60–80 km increased
by a factor of about 10 and 100 for flares with radiation flux densities 5·10−2 and 3·10−1
erg/(cm
2·s) in the wavelength range 0.5–4.0 Å which took place in January 19 and 20, respectively.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 1, pp. 1–8, January 2007. 相似文献
7.
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
8.
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.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 8, pp. 695–708, August 2007. 相似文献
9.
A. V. Ryabov S. M. Grach A.V. Shindin D. S.Kotik 《Radiophysics and Quantum Electronics》2011,54(7):441-451
We present the results of experimental studies of artificial large-scale irregularities of the ionospheric electron number
density with dual-frequency GPS diagnosis. The total electron content was analyzed in the GPS signal trajectory when the satellites
passed over the heated region. Spectral composition of the observed variations was determined by wavelet analysis. Characteristic
scales of artificial irregularities of the electron number density in the F layer are estimated. It is experimentally proved that the irregularities remain for at least 15–20 min after the transmitter
is switched off. A more confident excitation and increased intensity of the irregularities were also confirmed when the beam
was inclined south of the magnetic-zenith direction. 相似文献
10.
C. Lazzaroni P. Chabert A. Rousseau N. Sadeghi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(3):555-563
A microplasma is generated in the microhole (400 μm diameter) of a
molybdenum-alumina-molybdenum sandwich (MHCD type) at medium pressure
(30–200 Torr) in pure argon. Imaging and emission spectroscopy have been
used to study the sheath and electron density dynamics during the stationary
normal regime and the self-pulsing regime. Firstly, the evolution of the
microdischarge structure is studied by recording the emission intensity of
the Ar (5p[3/2]1–4s[3/2]1)_{1}) line at 427.217 nm, and Ar+
(4p′
2P3/2–4s′
2D5/2)_{5/2}) line at 427.752 nm. The maximum of
the Ar+ line is located in the vicinity of the sheath-plasma edge. In
both regimes, the experimental observations are consistent with the position
of the sheath edge calculated with an ionizing sheath model. Secondly, the
electron density is recorded by monitoring the Stark broadening of the
Hb_\beta-line. In the self-pulsing regime at 150 Torr, the electron
density reaches its maximum value of 4 × 1015 cm-3, a few
tens of ns later than the discharge current maximum. The electron density
then decays with a characteristic decay time of about 2 μs, while the
discharge current vanishes twice faster. The electron density in the
steady-state regime is two orders of magnitude lower, at about 6–8 ×
1013 cm-3. 相似文献
11.
V. A. Alimov F. I. Vybornov E. N. Myasnikov A. V. Rakhlin 《Radiophysics and Quantum Electronics》2008,51(11):874-879
We show the results of the first experimental studies of the multifractal structure of the developed artificial ionospheric
turbulence. As a result of the special multifractal analysis of the recorded amplitudes of signals from the orbital satellites,
which were obtained during the experiments on radio tomography of the irregularities excited in the ionosphere by the powerful
mid-latitude heating facility “Sura,” it is found that the characteristic multifractal structure of these records is caused
by the nonuniform spatial distribution of the small-scale fluctuations of the electron number density in the artificial irregularities
of the ionospheric plasma. Comparative analysis is performed for the multifractal spectra of fluctuations of both the amplitudes
and energies of signals received from the orbital satellites upon radio transmission probing of the region of artificial ionospheric
turbulence by these signals at three observation points located near the “Sura” heating facility and spaced apart to a distance
of about 100–150 km.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 11, pp. 970–976, November 2008. 相似文献
12.
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
13.
V. P. Burmaka I. F. Domnin V. P. Uryadov L. F. Chernogor 《Radiophysics and Quantum Electronics》2009,52(11):774-795
We describe the results of using the incoherent scatter technique to observe time-altitude variations in regular parameters
of the ionospheric plasma and wave disturbances, which accompanied periodic modification of the near-Earth plasma by radio
waves emitted by the “Sura” facility. A distinctive feature of the experiments was that the processes in the ionosphere were
diagnosed at a distance of about 1000 km from the facility. It was found that the spectrum composition of wave disturbances
in the electron density was changing noticeably during the active experiment. Quasi-periodic processes in the ionosphere were
observed with a delay of about 40–60 min. The relative amplitude of wave disturbances was equal to 0.02–0.10, and the periods
were equal to 30, 60, 120, and 150–180 min. The observed effect can be explained by the generation and/or amplification of
traveling ionospheric disturbances. The results of theoretical estimations agree well with the observational data. 相似文献
14.
V. E. Kunitsyn E. D. Tereshchenko E. S. Andreeva V. F. Grigor’ev N. Yu. Romanova M. O. Nazarenko Yu. M. Vapirov I. I. Ivanov 《Moscow University Physics Bulletin》2009,64(6):661-663
The results of studying the structure of the ionospheric plasma distribution from data obtained at the transcontinental Russian
radio tomographic chain, which is the world’s longest, are presented. The 4000 km long tomographic chain extends from the
Svalbard Archipelago to Sochi. The unique feature of this upgraded radio tomographic system is that for the first time observations
cover a wide sector of the ionosphere from high latitudes (polar cap and auroral region) to low latitudes. This allows us
to study the transfer of perturbations in the system auroral-subauroral-midlatitude-low latitude ionosphere, and to analyze
ionospheric electron density distributions in different latitudinal regions as a function of different external factors and
solar-geophysical conditions. The first recent results speak for a complex structure of the ionospheric plasma, even in quiet
geophysical conditions (K
p
< 2.) 相似文献
15.
We present the results of studying the multifractal structure of intermittency in a developed ionospheric turbulence during
special experiments on radio-raying of the midlatitude ionosphere by signals from orbital satellites in 2005–2006. It is shown,
in particular, that the determination of multidimensional structural functions of the energy fluctuations of received signals
permits one to obtain the necessary information on multifractal spectra of the studied process of radio-wave scattering in
the ionosphere. Experimental data on multifractal spectra of slow fluctuations in the received-signal energy under conditions
of a developed small-scale turbulence are compared with the existing concept of the radio-wave scattering within the framework
of the statistical theory of radio-wave propagation in the ionosphere. It is inferred that under conditions of a developed
ionospheric turbulence, the multifractal structure of the intermittency of slow fluctuations in the received-signal energy
is a consequence of the intermittency of small-scale fluctuations in the electron number density of the ionospheric plasma
on relatively large spatial scales of about several ten kilometers.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 6, pp. 485–493, June 2008. 相似文献
16.
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
17.
We present the results of experimental studies of the spectra of the stimulated electromagnetic emission excited in the ionosphere
by powerful radio waves during the pump wave frequency sweeping near the forth (n = 4) and fifth (n = 5) harmonics of the electron cyclotron frequency nf
ce. The frequency sweep was carried out for long (continuous) pumping in vertical and inclined directions (at 14° and 18° south
of the zenith), as well as for the pulse diagnostic wave both with and without additional pumping far from the gyroharmonics.
The dependences of the spectral features of the stimulated electromagnetic emission on the ratio between the pump-wave frequency
f
0 (or on the diagnostic-wave frequency fDW) and nf
ce were analyzed. It is found that near the multiple gyroresonance, different spectral features of the stimulated emission are
quenched at the same frequency for different pump-wave frequencies. For a sufficiently large inclination of the pump wave
beam from the vertical direction, the intensity of the stimulated electromagnetic emission is notably decreased for f
0 ≲ nf
ce as compared with f
0 > nf
ce.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 6, pp. 461–476, June 2008. 相似文献
18.
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
19.
Determination of the optimal parameters for the fabrication of ZnO thin films prepared by spray pyrolysis method 总被引:1,自引:0,他引:1
In this work, ZnO thin films have been prepared by spray pyrolysis deposition method on the glass substrates. The effect of
deposition parameters, such as deposition rate, substrate temperature and solution volume has been studied by X-ray diffraction
(XRD) method, UV–Vis–NIR spectroscopy, scanning electron microscopy (SEM), and electrical measurements. The XRD patterns indicate
polycrystalline wurtzite structure with preferred direction along (0 0 2) planes. Thin films have transparency around 90%
in the visible range. The optical band gap was determined at 3.27 eV which did not change significantly. Evolution of electrical
results containing the carriers’ density, sheet resistance and resistivity are in agreement with structural results. All the
results suggest the best deposition parameters are: deposition rate, R = 3 ml/min, substrate temperature, T
s = 450°C and thickness of the thin films t = 110–130 nm. 相似文献
20.
We consider the problem of obtaining reliable values of the local-spectrum indices of the electron number density fluctuations
for small-scale ionospheric turbulence. It is shown that the use of a multifractal analysis in combination with the synchronous
correlation processing of the received signals in the experiments on remote radio sounding of the ionosphere by satellite
signals permits one to solve the posed problem. In this case, the true values of the local-spectrum indices of small-scale
ionospheric turbulence, which are measured in such specialized experiments under natural conditions and during modification
of the ionosphere by high-power HF radio emission, can differ notably from their standard values obtained within the framework
of the classical method of radio scintillations, in which only correlation processing of the data is used.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 7, pp. 571–574, July 2008. 相似文献