Showing papers in "Radiophysics and Quantum Electronics in 2012"
TL;DR: In this article, a three-cavity gyroklystron was used to achieve a peak output power of 340 kW with 27% efficiency, 23dB saturated gain, and 0.41% bandwidth with a 75kV, 17-A electron beam.
Abstract: We present experimental results for a 93.2-GHz gyroklystron amplifier operated in the high-order TE021 cavity mode in a cryomagnet. In a three-cavity gyroklystron, a peak output power of 340 kW with 27% efficiency, 23-dB saturated gain, and 0.41% (380 MHz) bandwidth was obtained with a 75-kV, 17-A electron beam. The output-power and efficiency restriction was due to the selfexcitation of the TE021 operating mode in the output cavity. The influence of the electron beam current and intermediate cavity Q-factor on output characteristics of a three-cavity gyroklystron has been studied experimentally.
21 citations
TL;DR: In this article, the authors considered double and triple collisional interactions of molecules in a gas and derived the coefficients of the virial equation of state to dimer and trimer equilibrium constants.
Abstract: We consider all kinds of double and triple collisional interactions of molecules in a gas. Relation of the coefficients of the virial equation of state to dimer and trimer equilibrium constants is analyzed. The “excluded volume” for water vapor is estimated quantitatively. The volume is interpreted as an effective volume which is characterized by the range of molecular repulsive forces and is related to the collisional interaction of free monomers. Empirical data on water vapor in thermodynamic equilibrium are used for determination of the second and third virial coefficients, which serve for estimating the upper limits of the dimer and trimer equilibrium constants of water in the temperature range 273–1273 K.
21 citations
TL;DR: In this article, the authors present an overview of the onboard receiving complex of the millimetron space observatory in the development phase of its preliminary design, and present the basic parameters of onboard equipment planned to create and required for astrophysical observations.
Abstract: We present an overview of the state of the onboard receiving complex of the Millimetron space observatory in the development phase of its preliminary design. The basic parameters of the onboard equipment planned to create and required for astrophysical observations are considered. A review of coherent and incoherent detectors, which are central to each receiver of the observatory, is given. Their characteristics and limiting parameters feasible at the present level of technology are reported.
21 citations
TL;DR: In this article, the main trends in the development of gyrotrons of different frequency ranges and different levels of output power are discussed, as well as major problems that hinder the further progess in gyroscopic devices toward higher frequencies and capacities.
Abstract: Based on a retrospective analysis of the domestic and foreign works dealing with a variety of gyrotron applications and performed in the past decades, we show the main trends in the development of gyrotrons of different frequency ranges and different levels of output power. The main areas of application of modern gyrotrons and the specific requirements of each field are described. An overview of recent achievements, as well as major problems that hinder the further progess in gyroscopic devices toward higher frequencies and capacities is given. The methods of solution of these problems by the world’s leading research organizations and manufacturing companies are considered.
19 citations
TL;DR: In this paper, the structure and dynamics of the HF-heated volume above the Sura facility obtained in 2010 by measurements of ionospheric airglow in the red and green lines of atomic oxygen.
Abstract: We present the results of studying the structure and dynamics of the HF-heated volume above the Sura facility obtained in 2010 by measurements of ionospheric airglow in the red (λ = 630 nm) and green (λ = 557.7 nm) lines of atomic oxygen. Vertical sounding of the ionosphere (followed by modeling of the pump-wave propagation) and measurements of stimulated electromagnetic emission were used for additional diagnostics of ionospheric parameters and the processes occurring in the heated volume.
19 citations
TL;DR: In this article, the results of observations of variations in the Doppler-frequency shift of electromagnetic radiation of decameter waves reflected from the ionosphere during the plasma modification by high-power radio-frequency radiation from the “Sura” facility and in reference days are presented.
Abstract: The results of observations of variations in the Doppler-frequency shift of electromagnetic radiation of decameter waves reflected from the ionosphere during the plasma modification by highpower radio-frequency radiation from the “Sura” facility and in reference days are presented. The distance from the facility to the diagnostic tools (Doppler radar) was about 1000 km. The traveling ionospheric disturbances corresponding to a delay time of about 50 min with respect to the time of switching high-power periodic radiation and a propagation velocity of 300–400 m/s were observed. The relative amplitude of the electron-density perturbations was 1–4 %, while their oscillation period amounted to tens of minutes. The parameters of the traveling ionospheric disturbances significantly depended on the “Sura” facility radiation mode.
18 citations
TL;DR: In this article, the main stages of the development of a gyrotron in the sub-terahertz band with a power of several hundreds of kilowatts, a duration of the output radiation pulses of about 10μs, and the generation frequency corresponding to an atmospheric transparency window are described.
Abstract: We describe the main stages of the development of a gyrotron in the sub-terahertz band with a power of several hundreds of kilowatts, a duration of the output radiation pulses of about 10 μs, and the generation frequency corresponding to an atmospheric transparency window. The gyrotron having a working frequency of 0.67 THz, a power of 200–300 kW, and the focal diameter of the output beam 1–2 mm can be used to detect sources of ionizing radiation from a distance of several tens of meters. The detection principle is based on the appearance of a microwave frequency discharge in the focal spot if the number of free electrons exceeds the natural background by 1–2 orders of magnitude. The electron-optical system of such a gyrotron has been calculated and optimized. The scenario of the gyrotron switch-on has been analyzed for the electron beam formed in such a system, and the possibility of stable single-mode generation on the TE31.8 mode is demonstrated. The results of analysis of thermal loads, which demonstrate their acceptable level in the cavity and the tube cavity for pulse durations of about 10 μs are presented.
17 citations
TL;DR: In this paper, an integral representation in the form of a single-time weighted Fourier transform (the so-called Fresnel transform) is developed from the obtained integral representation.
Abstract: We consider propagation of waves in a medium with irregularities located at relatively long distances from the source and the observer within the paraxial approximation. The asymptotic approximation, which was obtained earlier by using a double weighted Fourier transform, is reduced to form that is convenient for application under these conditions. By using the stationary-phase method, an integral representation in the form of a single-time weighted Fourier transform (the so-called Fresnel transform) is developed from the obtained integral representation. The conditions of the transition of this representation to the phase-screen method determine the conditions of the applicability of the latter and the criteria for selection of the screen location during higherresolution diagnostics of a non-uniform medium. The results of numerical spatial processing of the signal, which improves the resolution of diagnostics of non-uniform media, are presented.
15 citations
TL;DR: In this paper, it was shown that the scattering from strongly nonlinear waves within the centimeter and, partially, decimeter wavelength range is due to the effects of their micro-breaking and the bound (spurious) capillary ripples excited on their profile.
Abstract: We performed laboratory experiments to study peculiarities of radar scattering of microwave radiation by strongly nonlinear (breaking) gravity-capillary waves on the water surface. It was shown that the scattering from strongly nonlinear waves within the centimeter and, partially, decimeter wavelength range is due to the effects of their “micro-breaking” and the bound (spurious) capillary ripples excited on their profile. The phase velocity of the ripples coincides with the phase velocity of the generating waves. The scattering by meter waves, which at high amplitudes are characterized by strong breaking with tipping of the crest, is determined mainly by the quasi-linear capillary ripples, whose phase velocity is determined by the dispersion relation for free surface waves. In the case of the waves within an intermediate range, which have lengths from several decimeters to one meter, both the spurious and free capillary ripples contribute to the scattering.
12 citations
TL;DR: In this article, the authors propose a method for the development of an approximate solution of the Maxwell equations in smoothly inhomogeneous anisotropic gyrotropic media with allowance for aberrations, spatial dispersion, and absorption.
Abstract: In this series of papers, we propose a method for the development of an approximate solution of the Maxwell equations in smoothly inhomogeneous anisotropic gyrotropic media with allowance for aberrations, spatial dispersion, and absorption. The connection with the aberration-free approximation equations is shown. In the first paper of the series, we propose a procedure for the development of an approximate scalar wave equation aimed at description of the single-mode propagation of wave beams.
11 citations
TL;DR: In this article, the results of experimental studies of an artificial ionospheric turbulence were obtained using the radio-direction finder ionosonde with linear frequency chirp of output signal.
Abstract: We present the results of experimental studies of an artificial ionospheric turbulence, which were obtained using the radio-direction finder ionosonde with linear frequency chirp of output signal. Several scattered signals with close distance-frequency and angular-frequency characteristics were observed, which is related to radio-wave scattering by various clustered areas. The features of the aspect scattering of radio waves on the IZMIRAN–“Sura”–Rostov-on-Don path were simulated. The spatial dimensions and the structure of the region filled by small-scale artificial ionospheric irregularities are estimated. The displacement of some clusters from the main region is of the order of 10–40 km with the smaller and larger displacements observed in the daytime and evening ionospheres, respectively.
TL;DR: In this article, the authors present the results of studying simultaneously the dynamics of artificial plasma irregularities in the range of decameter scales and diagnostic stimulated electromagnetic emission of the ionosphere, which were obtained during heating experiments on the "Sura" facility and several remote points where aspect-scattered signals were received.
Abstract: We present the results of studying simultaneously the dynamics of artificial plasma irregularities in the range of decameter scales l⊥ ≈ 7–125 m being perpendicular to the magnetic field and diagnostic stimulated electromagnetic emission of the ionosphere, which were obtained during heating experiments on the “Sura” facility and several remote points where aspect-scattered signals were received. The daily dependence of the times of evolution and relaxation of the irregularities and the diagnostic emission of the ionosphere are analyzed and compared.
TL;DR: In this article, the authors present the results of experimental studies of the features of long-distance propagation of high-frequency radio waves on the large-extent subauroral Magadan-Rostov-on-Don and midlatitude Khabarovsk and Irkutsk trajectories using the ionosonde-finder with a chirp output signal.
Abstract: We present the results of experimental studies of the features of long-distance propagation of high-frequency radio waves on the large-extent subauroral Magadan–Rostov-on-Don and midlatitude Khabarovsk–Rostov-on-Don and Irkutsk–Rostov-on-Don paths, which were obtained using the ionosonde-finder with a chirp output signal. Anomalous (lateral) signals with delays of about 1–2 ms with respect to a direct signal, which arrive from the azimuths 10°–20°, are observed on the Magadan–Rostov-on-Don path. The lateral signals were observed in the morning and antemeridian hours in the time interval 08:00–10:40 MSK. In the evening and night hours, the lateral signals were not observed. During magnetic activity, the amplitude of the lateral signals was greater than that observed prior to a magnetic storm by 5–10 dB. Location of the ionospheric-perturbation regions responsible for the appearance of the lateral signals was determined as φgeogr ≈ 69°–71°N (φmagn ≈ 65°–66°N), and λ ≈ 51°–58°E. The mechanisms of the lateral-signal propagation due to lateral refraction of radio waves on patches with enhanced electron number density and due to scattering of radio waves from small-scale irregularities are considered.
TL;DR: It is shown that the inclusion of the axonal interaction of neurons of different layers plays a significant role in the formation of spatio-temporal activity of the inferior olive neurons.
Abstract: We propose a discrete model of the olivo-cerebellar system. The model consists of three layers of interacting elements, namely, inferior olive neurons, Purkinje cells, and deep cerebellar nuclear neurons combined into a structure by axonal connections. Each element of the structure is described by a two-dimensional map with an individual set of parameters for each type of neurons. Dynamic properties of different types of neurons are described and spontaneous and stimulusinduced dynamics of the system is explored. Unlike the previously proposed models, this study takes into account the axonal interaction of neurons of different layers, as well as the interaction of the inferior olive neurons through electrical synapses with the property of plasticity. It is shown that the inclusion of these factors plays a significant role in the formation of spatio-temporal activity of the inferior olive neurons.
TL;DR: In this paper, the results of microwave observations of ozone radiation in the middle atmosphere during modification of the ionosphere by high-power short radio waves on March 27-28, 2011 were presented.
Abstract: We present the results of microwave observations of ozone radiation in the middle atmosphere during modification of the ionosphere by high-power short radio waves on March 27–28, 2011. The modification was performed on the “Sura” heating facility of the Radiophysical Research Institute (Nizhny Novgorod, Russia) by using two ozone meters oriented towards different regions in the sky. The effect of a decrease in the radiation intensity in the ozone line when the ionosphere is heated with high-power short-wave radio emission, which was discovered earlier, has been confirmed, and new data related to its characteristic have been obtained. A possible interpretation of this phenomenon is discussed.
TL;DR: In this article, the authors considered the possibilities of diagnostics of artificial ionospheric irregularities with the transverse size l⊥ ≈ 50-200 m, which are excited in the Earth's ionosphere by high-power short-wave radiofrequency radiation from the “Sura” facility using the method of vertical sounding of the ionosphere using the ionosonde located near the heating facility.
Abstract: In this work, we consider the possibilities of diagnostics of artificial ionospheric irregularities with the transverse size l⊥ ≈ 50–200 m, which are excited in the Earth’s ionosphere by highpower short-wave radio-frequency radiation from the “Sura” facility using the method of vertical sounding of the ionosphere by the ionosonde located near the heating facility. Some results of the performed studies showing the features of such a diagnostics are presented.
TL;DR: In this paper, a non-quasistationary evolution of the nearly limiting Gardner-equation solitons, caused by the variable parameters of the medium is considered.
Abstract: Non-quasistationary evolution of the nearly limiting Gardner-equation solitons, which is caused by the variable parameters of the medium is considered. The proposed approximate description of such a process is based on representing the Gardner-equation solitons as compound formations formed by different-polarity kinks. The equations describing evolution of both the field drops in the kinks and the slowly varying (compared with the drops) fields connecting the kinks are derived. The problem of the soliton evolution in the case of a linear (in time) change of the cubic nonlinearity coefficient of the Gardner equation is solved analytically. The obtained approximate solution is compared with the results of the previous direct numerical integration of this problem.
TL;DR: In this paper, a superheterodyne receiver with a Schottky-diode for a new mobile microwave ozonometer operated at a frequency of 142.2 GHz is described.
Abstract: We describe a low-noise superheterodyne receiver with a Schottky-diode for a new mobile microwave ozonometer operated at a frequency of 142.2 GHz, which is designed to measure the vertical profile of ozone distribution in the stratosphere and mesosphere. Calculated and experimental characteristics of the input quasioptical units of the receiver at the Gaussian beams and the measurement results for the directional pattern of the receiver antenna and the noise temperature of the receiver are presented.
TL;DR: In this article, the results of filtering in the range of periods 5.6-6.7 min of temporal variations in the Doppler frequency shift of the ionosphere-reflected radio signals from the high-frequency vertical ionospheric-sounding radar located near the city of Kharkov during ionosphere plasma modification by high-power periodic (with 6-min period) radio waves of the Sura facility.
Abstract: We present the results of filtering in the range of periods 5.6–6.7 min of temporal variations in the Doppler frequency shift of the ionosphere-reflected radio signals from the high-frequency vertical ionospheric-sounding radar located near the city of Kharkov during ionospheric plasma modification by high-power periodic (with 6-min period) radio waves of the Sura facility. It is found that switching on and off a series of pulses with 3-min duration and the same pause launched a damped wave process with 6-min period, a delay time of about 30–50 min, and an apparent propagation velocity of about 320–530 m/s. The quasi-periodic variation amplitude of the Doppler frequency shift was 10–40 MHz. The corresponding relative-perturbation amplitude of the electron number density was about 0.1–0.3%. Detected oscillations is evidence that damped infrasound density waves can be generated in the upper atmosphere.
TL;DR: In this paper, the authors present the results of analysis of helio-geophysical conditions for the experiments performed in 2007-2010 to study modification of the ionosphere by high-power radio emission of the “Sura” heating facility.
Abstract: We present the results of analysis of helio-geophysical conditions for the experiments performed in 2007-2010 to study modification of the ionosphere by high-power radio emission of the “Sura” heating facility. The feature of the experiments is that the operating frequency of the facility exceeded the upper-hybrid frequency for the F2 layer maximum in the ionosphere. All the experiments were performed in the local-time sector of the Harang discontinuity (i.e., from 21:00 to 00:00, local time) to ensure the most probable influence of the facility operation on the onset of natural processes in the subauroral region of the ionosphere. At least two experiments were found to demonstrate that the observed substorm activity in the region of the modification produced by the facility could be stimulated by its operation. The results of the ground- and satellite-based measurements, both in the vicinity of the “Sura” facility and in the magnetically conjugate region, confirm the conclusion about the possibility of substorm localization by this facility.
TL;DR: In this paper, the authors describe a facility for testing the properties of different objects affected by a sequence of high-power pulses of the microwave electromagnetic field, which is implemented due to the power level and stability of the single-mode generation of a free electron maser with an output frequency of 30 GHz.
Abstract: We describe a facility for testing the properties of different objects affected by a sequence of highpower pulses of the microwave electromagnetic field. The facility performance is implemented due to the power level and stability of the single-mode generation of a free electron maser with an output frequency of 30 GHz, which have been achieved at the Joint Institute for Nuclear Research and the Institute of Applied Physics of the Russian Academy of Sciences. This paper describes the experiments on studying of the thermal fatigue of the copper surface in a test cavity, which models the thermal regime of the accelerating structure of the CLIC project (CERN), as well as the experiments on irradiation of biological tissues, metal films, and nanoclusters.
TL;DR: In this paper, the authors consider sporadic radio emission which precedes recording of geoeffective coronal mass ejections, using the data of broadband patrol observations of the Sun in the centimeter-, decimeter-, and meter-wave ranges in some periods of the XXIst-XXIIIrd solar activity cycles.
Abstract: We consider sporadic radio emission which precedes recording of geoeffective coronal mass ejections, using the data of broadband patrol observations of the Sun in the centimeter-, decimeter-, and meter-wave ranges in some periods of the XXIst–XXIIIrd solar-activity cycles. The total amount of used information instruments covers 339 events and includes the data from the radioastronomical facility “Zimenki” of the Radiophysical Research Institute and from the world solar service in the radio-frequency range, as well as the catalogs of coronal mass ejections recorded by the SMM and SOHO/LASCO instruments. On the basis of statistical analysis, we reveal the regular features in the characteristics of sporadic microwave emissions observed in the twohour interval before the coronagraph detection of geoeffective coronal mass ejections, which were defined as radio precursors of such coronal mass ejections. The revealed features in the characteristics of the radio precursors of geoeffective coronal mass ejections involve the presence of the broadband centimeter–decimeter radio emission for over 10 min in the stage preceding the coronal ejection redetection by coronagraphs. Such radio precursors are shown to precede loop-like halo, and partial halo coronal mass ejections, which have maximum potential geoeffectiveness. The radio-emission behavior, which does not meet the established regular features, is also analyzed.
TL;DR: In this paper, a modification of the resonant "cuvetteless" method for measuring refractive and absorption indices of liquid dielectrics was proposed, which does not require a priori information on the liquid-layer thickness.
Abstract: We consider a modification of the resonant “cuvetteless” method for measuring refractive and absorption indices of liquid dielectrics, which does not require a priori information on the liquid-layer thickness. The results of precision measurements of the values of the refractive index and the loss tangent of modern liquid dielectrics in millimeter and submillimeter wave ranges are shown. These materials are supposed to be used for both cooling the elements of high-power gyrotrons (with an output power of about a megawatt in the continuous mode), in which these liquids directly interact with electromagnetic radiation, and microwave-energy absorption in various kinds of calorimetric measuring loads and end loads absorbing the entire radiated power.
TL;DR: In this paper, the absorption and refraction spectra of nanostructured aluminum oxyhydroxides and oxides and their chemical modifications by silicon oxide were studied using pulsed terahertz spectroscopy.
Abstract: Using the method of pulsed terahertz spectroscopy, we study the absorption and refraction spectra of nanostructured aluminum oxyhydroxides and oxides and their chemical modifications by silicon oxide. The obtained experimental results were used in the Bruggeman model of effective medium approximation for calculating the absorption and refraction spectra of fibrils, which are the basic structural elements of these nanomaterials. The studies performed in the temperature range 20–1200°C allow us to follow variations in the absorption coefficients and refractive indices and their relation to variations in the structural-phase state and the chemical content of nanostructured aluminum oxyhydroxide and oxide and their chemical modifications by silicon oxide. Special attention is paid to studying the influence of the content and state of water and its derivatives in the structure and on the surface of nanomaterial. The obtained results make it possible to quantify the absorption and refraction in materials and media created on the basis of nanostructured aluminum oxyhydroxide and oxide and their chemical modifications by silicon oxide.
TL;DR: In this article, a new spectral structure appeared in quasi-harmonic oscillations of the noise intensity with frequency scales a factor of 3 to 4 smaller than the scales of an ordinary spectral resonance structure.
Abstract: Using the data of continuous monitoring of low-frequency background noise at the station “Novaya Zhizn” (Nizhny Novgorod Province, Russia) for 2006–2010, we studied a new spectral structure appearing in quasi-harmonic oscillations of the noise intensity with frequency scales a factor of 3 to 4 smaller than the scales of an ordinary spectral resonance structure. The features of the fine spectral structure were studied, i.e., frequency of occurrence, diurnal dynamics, and the frequency bandwidth. The features of an ordinary resonance structure were also studied in the “fine structure” appearance and the transition solar-activity periods (2010–2011). Using the calculations of the low-frequency magnetic fields propagating in a spherically horizontally inhomogeneous Earth–ionosphere waveguide, we analyzed the possible influence of the nonlocal ionospheric properties on the magnetic-component spectra in the range 0.1–20 Hz. It is shown that the influence of the nonlocal ionospheric properties on the extremely low-frequency spectra can be observed in the presence of an ionospheric horizontal inhomogeneity due to different shapes of the ionospheric-parameter profiles along the radio-wave propagation path.
TL;DR: In this article, the authors present the results of observations of the wave disturbances in the ionospheric F region over the city of Kharkov, which accompanied the impact on the ionosphere by high-power radio emission of the Sura heating facility located about 960 km from the observation site.
Abstract: We present the results of observations of the wave disturbances in the ionospheric F region over the city of Kharkov, which accompanied the impact on the ionosphere by high-power radio emission of the Sura heating facility located about 960 km from the observation site. Enhancement of the wave activity in the heater operation intervals is detected. A 1.5–4-fold increase in the relative amplitude of the wave disturbance with a period of about 30 min close to the Sura operation mode at altitudes 160–235 km is revealed. The parameters of this disturbance are evaluated. It is shown that this effect can be due to the propagation of internal gravity waves in the atmospheric waveguide having about 200 km in height and 80–100 km in width. The efficiency of comprehensive analysis of the experimental data which we used to reveal and estimate the parameters of the wave disturbances with a small (a few percent) relative amplitude is demonstrated.
TL;DR: In this paper, the authors describe the observation results of ionospheric disturbances at altitudes of 100 to 140 km, which occurred at a distance of about 1000 km from the Sura facility.
Abstract: We describe the observation results of ionospheric disturbances at altitudes of 100 to 140 km, which occurred at a distance of about 1000 km from the Sura facility. The observations have been made using the incoherent scatter radar located near Kharkov. The electron density increase by 10–70 % had a temporal duration of 10–20 min and accompanied the high-power HF heating. The time of disturbance evolution was about 10 min. The observation effect can be explained by the intensification of the subsystem coupling in the ionosphere–magnetosphere–upper atmosphere– ionosphere system, which leads to a precipitation of energetic electrons from the magnetosphere. Parameters of the precipitating particles and precipitation-produced ionization are estimated.
TL;DR: In this paper, the authors proposed to couple two coaxial waveguides by 2D periodic perforation in the common wall in order to ensure selective coupling between two waves propagating in these waveguide.
Abstract: We propose to couple two coaxial waveguides by 2D periodic perforation in the common wall in order to ensure selective coupling between two waves propagating in these waveguides. In the experiment at a frequency of 10 GHz, the H
01 mode of the internal waveguide was converted to the rotating H
51 mode of the external waveguide with a power loss of several percent.
TL;DR: The diplexer is a four-mirror quasi-optical traveling-wave resonator, in which the transmission lines are connected by a pair of corrugated mirrors forming the resonator.
Abstract: We propose a description of the diplexer, a device for control of high-power beams of millimeterwave radiation in electron-cyclotron heating systems for controlled fusion facilities. The diplexer is a four-mirror quasi-optical traveling-wave resonator, in which the transmission lines are connected by a pair of corrugated mirrors forming the resonator. In this paper, we develop a theory of such systems. An integral equation describing the beams of electromagnetic waves in the resonator in paraxial approximation and defining the diplexer characteristics with allowance for losses is deduced. The losses are due to the ohmic dissipation, diffraction, and limited size of the mirrors, as well as the difference between the widths and wave fronts of the diplexer resonator modes and the transmission lines. The integral equation is numerically solved by the iteration method using software with imaging. The eigenfrequencies of such a system with allowance for the vector character of the wave beams are found. Conditions under which the diplexer can be operated irrespective of the polarization of the incident radiation are determined.
TL;DR: In this paper, the effects of different-scale artificial plasma density irregularities excited by HF modification of the ionospheric F2 region under conditions where the frequency of the O-mode pump wave is close to the fourth gyroharmonic frequency of electrons in the pump wave were considered.
Abstract: Gyroharmonic features of the different-scale artificial plasma-density irregularities excited by HF modification of the ionospheric F2 region under conditions where the frequency of the O-mode pump wave is close to the fourth gyroharmonic frequency of electrons in the pump wave—plasma interaction region are considered.