Density ducts formed by heating the Earth’s ionosphere with high-power HF radio waves

The parameters of plasma disturbances at altitudes 660 and 840 km, measured by the instruments onboard the French DEMETER satellite and the US DMSP satellites passing through the magnetic flux tube footed at the region of intense modification of the F ₂ ionospheric layer by the high-power HF radio waves of the Sura heating facility, are presented. The formation of artificial enhanced-density plasma ducts in the outer ionosphere is observed experimentally. Conditions facilitating the formation of such ducts are pointed out.     

Excitation of Alfvén vortices in the ionosphere by the magnetospheric convection

We analyze conditions for excitation of ULF waves in the ionospheric Alfvén resonator (IAR), taking into account the altitude-inhomogeneous profile of the magnetospheric convection velocity. This profile is formed as a result of interaction of the convective flow with the neutral atmosphere at altitudes 90–150 km. ULF waves comprise oblique Alfvén waves, trapped into the IAR, and ionospheric drift waves, which are in resonance with them. These waves together form strongly anisotropic, closed current loops, whose scale along the magnetic field greatly exceeds their transverse scale, i.e., l_z ≫ l_⊥, and can be considered Alfvén vortices. Within the framework of the proposed model of the ionosphere, we study the instability threshold and the amplitude growth rate of the Alfvén vortices as functions of different parameters (wave vector k_22A5, angle between the wave vector and the convection velocity, ratio of the Alfvén-wave and Pedersen conductivities, etc.). Some estimates are given in application to the observed small-scale field-aligned currents in the auroral ionosphere. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 5, pp. 376–390, May 2008.     

Satellite measurements of plasma-density perturbations induced in the topside ionosphere by high-power HF radio waves from the “Sura” heating facility

We report on the French DEMETER and American DMSP satellite measurements of largescale field-aligned plasma-density perturbations (ducts) induced in the topside ionosphere by the ionospheric F ₂-layer pumping by means of high-power HF radio waves from the “Sura” heating facility. Characteristics of such plasma perturbations and conditions of their formation are determined. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 11, pp. 915–924, November 2008.     

Spatial-frequency characteristics of radio emission induced by interaction of an extensive air shower with the Earth’s surface

The spatial directional pattern of the radio emission induced by interaction of the excess electrons of an extensive air shower with the Earth’s surface was found in the approximation of perfect soil conductance. The results made it possible to determine the frequency range (≈0.2–1 MHz), within which the radio emission of the shower is maximum, provided that this emission mechanism is valid. In addition, it became possible to explain the previously observed lack of direct proportionality between the shower energy and the radio signal amplitude. It was found that this disproportionality is caused mainly by the high directivity of low-frequency (0.2–3 MHz) radiation patterns within a wide range of the values of the axial tilt.     

Simulation of the electric field in Earth’s ionosphere during a geomagnetic storm

Previously, a global self-consistent model of the thermosphere, ionosphere, and protonosphere (GSM TIP) was used to study the ionospheric effects of geomagnetic storms in 2005, 2006, 2010, and 2011. In these studies, the input parameters of the model were specified using different dependences of variations of the potential difference across the polar caps and of the spatial distribution of Region 2 field-aligned currents during geomagnetic storms on the geomagnetic activity indices, solar wind parameters, and interplanetary magnetic field parameters. In the present work, we have tried to examine how correct was the choice of these relationships and how faithful are the obtained global distributions of the electric field in the ionosphere. For this, we present the results of a comparative analysis of the electric field in the ionosphere during geomagnetic storms of May 2–3, 2010, obtained using two models (GSM TIP and LC06) based on different approaches to solving this problem.     

Precipitation of Energetic Electrons from the Earth’s Radiation Belt Stimulated by High-Power HF Radio Waves for Modification of the Midlatitude Ionosphere

Radiophysics and Quantum Electronics - Based on the results of the experiments performed in 2005–2010 within the framework of the Sura—DEMETER program, we analyze the features of the...     

Reflectionless propagation of acoustic waves through the Earth’s atmosphere

The vertical propagation of acoustic waves in the inhomogeneous compressible atmosphere has been studied in the framework of the linear theory of ideal hydrodynamics. It has been shown that the initial equations under certain conditions can be reduced to the Klein-Gordon equation with constant coefficients. Its solutions describe traveling waves with a variable amplitude and wavenumber that are not reflected in the atmosphere despite its strong inhomogeneity. The wave energy flux at such reflectionless profiles holds, providing the possibility of the energy transfer to high altitudes. It has been shown that the Standard Earth Atmosphere is approximated well by four reflectionless profiles with small jumps in the gradient of the speed of sound. It is found that the Earth’s atmosphere is almost transparent in a wide frequency range; this feature explains the observation data and conclusions made on the basis of numerical solutions in the framework of the initial equations.     

Characterization of Porous Materials by Magnetic Relaxometry in the Earth’s Field

In this paper, it is shown how free induction decay signals recorded in the Earth’s magnetic field from water protons confined in porous media can be used to derive transversal relaxation times (T ₂) and their distributions. After T ₂ determination of six sintered glass samples with various pore sizes, the common theoretical model can be fitted to the data set. The T ₂ distribution of water protons in a bimodal porous system is analyzed and compared to mercury porosimetry results. The implications for the calculation of pore sizes and pore size distributions of porous media by this method are discussed.     

An implicit FDTD scheme for the propagation of VLF–LF radio waves in the Earth–ionosphere waveguide

A new finite-difference time-domain scheme is presented for the propagation of VLF–LF radio waves in the Earth–ionosphere waveguide. The new scheme relies on the implicit solution of the auxiliary equation that governs the current density in the ionosphere. The advantages and drawbacks of the new scheme are discussed. Its main advantage is its stability condition, which is the same as that of the FDTD method in a vacuum. This permits the time step of the calculation to be increased and then the overall computational time to be reduced. Numerical experiments demonstrate the accuracy of the new scheme and the reduction of the computational time.     

Efficient and rapid accuracy estimation of the Earth’s gravitational field from next-generation GOCE Follow-On by the analytical method

Firstly, a new analytical error model of the cumulative geoid height using the three-dimensional diagonal tensors of satellite gravity gradiometry (SGG) is introduced based on the variance-covariance matrix principle. Secondly, a study for the requirements demonstration on the next-generation GOCE Follow-On satellite gravity gradiometry system is developed using different satellite orbital altitudes and measurement accuracies of satellite gravity gradiometer by the new analytical error model of SGG. The research results show that it is preferable to design satellite orbital altitudes of 300 km-400km and choose the measurement accuracies of 10-13/s2 -10-15/s2 from satellite gravity gradiometer. Finally, the complementarity of the four-stage satellite gravity missions, including past CHAMP, current GRACE, and GOCE, and next-generation GOCE Follow-On, is contrastively demonstrated for precisely recovering the Earth’s full-frequency gravitational field with high spatial resolution.     

Exploration of the Townsend regime by discharge light emission in a gas discharge deviceExploration of the Townsend regime by discharge light emission in a gas discharge deviceExploration of the Townsend regime by discharge light emission in a gas discharge deviceExploration of the Townsend regime by discharge light emission in a gas discharge deviceExploration of the Townsend regime by discharge light emission in a gas discharge device

The Townsend discharge mechanism has been explored in a planar microelectronic gas discharge device （MGDD） with different applied voltages U and interelectrode distance d under various pressures in air. The anode and the cathode of the MGDD are formed by a transparent SnO2 covered glass and a GaAs semiconductor, respectively. In the experiments, the discharge is found to be unstable just below the breakdown voltage Ub, whereas the discharge passes through a homo- geneous stable Townsend mode beyond the breakdown voltage. The measurements are made by an electrical circuit and a CCD camera by recording the currents and light emission （LE） intensities. The intensity profiles, which are converted from the 3D light emission images along the semiconductor diameter, have been analysed for different system parameters. Dif- ferent instantaneous conductivity ~t regimes are found below and beyond the Townsend region. These regimes govern the current and spatio-temporal LE stabilities in the plasma system. It has been proven that the stable LE region increases up to 550 Torr as a function of pressure for small d. If the active area of the semiconductor becomes larger and the interlectrode distance d becomes smaller, the stable LE region stays nearly constant with pressure.     

On the Negatively Charged Layer of the Earth’s Electric Field

Based on the hydridic Earth model, we propose a hydridic model of the Earth’s electric field. The model predicts that the negative electrode of the Earth’s capacitor is located under the Earth’s crust and the Earth’s fluids carry a positive charge. We have observed an excess of positive charge in the Earth’s crust down to kilometer depths. The model explains the unitary variation of the fair-weather atmospheric electric field strength, the change in atmospheric electric field strength and the precipitation of high-energy electrons during earthquakes.     

On wave and rheidity properties of the Earth’s crust

The properties of the Earth’s solid crust have been studied on the assumption that this crust has a block structure. According to the rotation model, the motion of such a medium (geomedium) follows the angular momentum conservation law and can be described in the scope of the classical elasticity theory with a symmetric stress tensor. A geomedium motion is characterized by two types of rotation waves with shortand long-range actions. The first type includes slow solitons with velocities of 0 ≤ V_sol ≤ c0, max = 1–10 cm s^–1; the second type, fast excitons with V₀ ≤ V_ex ≤ V_S–V_P. The exciton minimal velocity (V₀ = 0) depends on the energy of the collective excitation of all seismically active belt blocks proportional to the Earth’s pole vibration frequency (the Chandler vibration frequency). The exciton maximal velocity depends on the velocities of S (V_S ≈ 4 km s^–1) and/or P (V_P ≈ 8 km s^–1) seismic (acoustic) waves. According to the rotation model, a geomedium is characterized by the property physically close to the corpuscular–wave interaction between blocks that compose this medium. The possible collective wave motion of geomedium blocks can be responsible for the geomedium rheidity property, i.e., a superplastic volume flow. A superplastic motion of a quantum fluid can be the physical analog of the geomedium rheid motion.     

Physical analysis on improving the recovery accuracy of the Earth’s gravity field by a combination of satellite observations in along-track and cross-track directions

The physical investigations on the accuracy improvement to the measurement of the Earth＇s gravity field recovery are carried out based on the next-generation Pendulum-A/B out-of-plane twin-satellite formation in this paper. Firstly, the Earth＇s gravity field complete up to degree and order 100 is, respectively, recovered by the collinear and pendulum satellite formations using the orbital parameters of the satellite and the matching accuracies of key payloads from the twin GRACE satellites. The research results show that the accuracy of the Earth＇s gravity field model from the Pendulum-A/B satellite formation is about two times higher than from the collinear satellite formation, and the further improvement of the determination accuracy of the Earth＇s gravity field model is feasible by the next-generation Pendulum-A/B out-of-plane twin-satellite formation. Secondly, the Earth＇s gravity field from Pendulum-A/B complete up to degree and order 100 is accurately recovered based on the orbital parameters of the satellite （e.g., an orbital altitude of 400 km, an intersatellite range of 100 km, an orbital inclination of 89° and an orbital eccentricity of 0.001）, the matching accuracies of space- borne instruments （e.g. 10-6 m in the intersatellite range, 10-3 m in the orbital position, 10-6 m/s in orbital velocity, and 10-11 m/s2 in non-conservative force）, an observation time of 30 days and a sampling interval of 10 s. The measurement accuracy of the Earth＇s gravity field from the next-generation Pendulum-A/B out-of-plane twin-satellite formation is full of promise for being improved by about l0 times compared with that from the current GRACE satellite formation. Finally, the physical requirements for the next-generation Pendulum-A/B out-of-plane twin-satellite formation are analyzed, and it is proposed that the satellite orbital altitude be preferably designed to be close to 400±50 km and the matching precision of key sensors from the Pendulum-A/B mission be about one order of magnitude higher tha     

ESR in the Earth’s magnetic field as a cause of dislocation motion in NaCl crystals

The resonance displacements of the dislocations, l ∼ 100 μm, in NaCl crystals placed in the crossed Earth’s magnetic field B _Earth and the ac field $ \tilde B $ \tilde B ≈ 3 μT of the variable frequency ν ∼ 10⁶ Hz have been discovered in the absence of any other impact on the crystals. Two peaks of the mean dislocation path l(ν) with the maxima at ν₁ = 1.3 MHz and ν₂ = 3 MHz have been observed for the field $ \tilde B $ \tilde B oriented along the vertical and horizontal components of B _Earth, respectively. The effect is explained by the depinning of the dislocations from the impurity centers after their structural transformation due to the ESR in the dislocation-impurity system in the crossed fields. The subsequent motion of the dislocations proceeds under the action of internal stress in the crystals. A physical model has been proposed to explain the strong anisotropy of the effect with respect to the mutual orientation of the dislocation lines and magnetic fields.     

A physical interpretation of Hubble’s law and the cosmological redshift from the perspective of a static observer

We derive explicit and exact expressions for the physical velocity of a free particle comoving with the Hubble flow as measured by a static observer, and for the frequency shift of light emitted by a comoving source and received, again, by a static observer. The expressions make it clear that an interpretation of the redshift as a kind of Doppler effect only makes sense when the distance between the observer and the source vanishes exactly.     

Measurement of the deflection of cosmic-ray electrons in the energy range 75–250 GeV by the Earth’s magnetic field with the PAMELA experiment

The deflection of electrons in the Earth’s magnetic field in the energy range 75–250 GeV (the so-called east-west effect) has been measured with the PAMELA satellite-borne experiment. The results are presented for various L-shells. The data obtained can be used to construct mathematical models that describe the structure of the Earth’s magnetic field and to refine the already existing models. These data can also be directly applied to estimate the positron fraction in cosmic-ray electron fluxes both in the PAMELA experiment and in other satellite-borne experiments.     

Search for the Relationship between Particle Precipitation from the Earth’s Radiation Belt and Cosmic Gamma-Ray Bursts

Physics of Atomic Nuclei - The article studies the relationship between particle precipitation from the Earth’s radiation belt and cosmic gamma-ray bursts. For this purpose, experimental...     

Latitude effect of muons in the Earth’s atmosphere during solar activity minimum

The results of muon flux measurements (E ≥ 70 MeV) in the atmosphere during solar activity minimum are reported. The measurements were performed during Antarctic sea expedition in 1975–1976 at several geomagnetic locations (from 1 to 14 GV). The experimental data obtained made it possible to determine the latitude effect of muons in the distribution at different levels in the atmosphere. The Geant4 program was used to simulate the galactic cosmic ray transport in the Earth’s atmosphere and evaluate the angular and spectral distributions (p, e^?/e⁺, photons, muons) at different atmospheric levels. The experimental and simulated results are in satisfactory agreement.     

Effect of sputtered Cu film’s diffusion barrier on the growth and field emission properties of carbon nanotubes by chemical vapor deposition

Growth of carbon nanotube (CNT) films with good field emission properties on glass is very important for low cost field emission display (FED) applications. In addition to Ni, Co and Fe, Cu can be a good catalyst for CNT growth on glass, but due to diffusion into SiO₂ it is difficult to control the CNTs density and uniformity. In this paper, four metal barrier layers (W, Ni, Cr, Ti) were deposited by dc magnetron sputtering on glass to reduce the Cu diffusion. As-grown CNT films showed various morphologies with the use of different barrier metals. CNTs with uniform distribution and better crystallinity can be synthesized only on Ti/Cu and W/Cu. Voltage current measurements indicate that better field emission properties of CNT films can be obtained on titanium and tungsten barriered Cu, while chromium and nickel are not suitable barrier candidates for copper in CNT-FED applications because of the reduced emission performance. PACS 81.05.Uw; 61.46.Fg; 85.45.Db; 66.30.-h