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Nizhniy Novgorod, Russia

Gurevich A.V.,RAS Lebedev Physical Institute | Karashtin A.N.,Radiophysical Research Institute
Physical Review Letters | Year: 2013

The particular electric pulse discharges are observed in thunderclouds during the initiation stage of negative cloud-to-ground lightning. The discharges are quite different from conventional streamers or leaders. A detailed analysis reveals that the shape of the pulses is determined by the runaway breakdown of air in the thundercloud electric field initiated by extensive atmospheric showers (RB-EAS). The high amplitude of the pulse electric current is due to the multiple microdischarges at hydrometeors stimulated and synchronized by the low-energy electrons generated in the RB-EAS process. The series of specific pulse discharges leads to charge reset from hydrometeors to the free ions and creates numerous stretched ion clusters, both positive and negative. As a result, a wide region in the thundercloud with a sufficiently high fractal ion conductivity is formed. The charge transport by ions plays a decisive role in the lightning leader preconditioning. © 2013 American Physical Society. Source

Vinyaikin E.N.,Radiophysical Research Institute
Radiophysics and Quantum Electronics | Year: 2012

In 2008 and 2009, when a deep solar-activity minimum was observed, the total electron content of the ionosphere was measured by the radioastronomy method using the ionospheric Faraday rotation of the polarization plane of a linear-polarized component of the diffuse radio-frequency (RF) radiation of the galaxy. In the measurements performed at a frequency of 290 MHz at the Radioastronomy observatory "Staraya Pustyn" of the Radiophysical Research Institute of Nizhny Novgorod, the previously studied region of the Celestial North Pole was used. The brightness temperature was calibrated by the Cassiopeia A radio source. The time dependence of the Cassiopeia The RF radiation stream density, which was obtained in the period of 1978-2011 from the measurement results at a frequency of 290 MHz, is shown. A new method of accounting for a spurious polarized signal allowing for its time dependence was developed and used, which makes it possible to improve the measurement frequency of the time variations of total electron content of the ionosphere. This method allowed us to more accurately measure the brightness temperature of the linearly polarized component of diffuse galaxy RF radiation in the direction of the Celestial North Pole, which amounted to 0.83 ± 0.07 K at a frequency of 290 MHz. For this region of the horizon, we demonstrate the spectra of the brightness temperature and the position angle of the polarization plane of the linearly polarized component of the galaxy diffuse RF radiation ranging from meter to centimeter wavelengths, which allows us to choose the required frequency for the measurements by the radioastronomy Faraday method in the future. The values of the total electron content of the ionosphere are compared with the corresponding values from the global ionospheric maps obtained from observations of the GPS satellite signals. The difference between the average values of total electron content of the ionosphere is 1. 9â̂™1012 cm-2 according to all radioastronomy measurements and the corresponding means from the global ionospheric maps. © 2012 Springer Science+Business Media New York. Source

Silin D.E.,RAS Institute of Applied Physics | Kozhevatov I.E.,Radiophysical Research Institute
Optics and Spectroscopy (English translation of Optika i Spektroskopiya) | Year: 2012

Based on the modification of a point diffraction interferometer, a method for measuring the optical fields from remote objects and external sources is developed. In this method, the reference beam is obtained from the studied beam by filtration of its spatial spectrum with a single-mode optical fiber. To eliminate the effect of phase errors caused by the nonideality of elements of the optical scheme on the measurement results, we developed a procedure of interferometer calibration that permits one to determine these errors with the aim of subtracting them from the measured field phase distributions. © Pleiades Publishing, Ltd., 2012. Source

Frolov V.L.,Radiophysical Research Institute
Radiophysics and Quantum Electronics | Year: 2012

Available experimental results on the modification of the Earth's ionosphere by high-power Xmode radio waves are reviewed. It is shown that the influence of such heating on the generation of artificial ionospheric turbulence is of complex nature and has different manifestations in various ionospheric regions and under different experimental conditions. The mechanisms of generation of the plasma disturbances under ionospheric heating by high-power X-mode radio waves, which have been proposed until recently, are discussed. © 2012 Springer Science+Business Media, Inc. Source

We present for the first time the experimental data on the frequency of ion–neutral collisions at the altitudes of the ionospheric E layer, which were obtained by the method of resonance scattering of the radio waves by artificial periodic irregularities of the ionospheric plasma. The measurements were carried out in different time periods from 1990 to 2012. Time and altitude dependences of the collision frequency are given. The dependence of the collision frequency on the solar and geomagnetic activity has been analyzed. © 2015, Springer Science+Business Media New York. Source

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