Yu. M. Mikhailov

Variations of ULF-VLF electric fields in the external ionosphere over powerful typhoons in Pacific Ocean

Abstract The results of the preliminary studies of spatial and spectral characteristics of the ULF-VLF electric field absolute values in the topside ionosphere over the Pacific Ocean aquatory at h = 1500–2500 km in the daytime and at h = 550–700 km in the nighttime in September 1990 are presented. The registration results of the E component of the field by the narrow-band filters at frequencies of 8, 20, 33, 50, 75, 150, 225, 433, 623, 970 Hz, 9.6 and 15 kHz installed on board the Intercosmos 24 satellite were used. The spectral distribution of the E component of the field both in the day and night time qualitatively agrees with the propagation theory of the ULF-VLF wave whistler mode through the ionosphere, but the anomalously high field values in the daytime contradict this theory and the experimental data available. This may be related to giant lightning discharges over typhoons and amplification of the signal by focusing of ray trajectories at the daytime and defocusing them at the nighttime near equatorial anomaly.

Electric and Electromagnetic Processes in the Near-Earth Atmosphere before Earthquakes on Kamchatka

Simultaneous records of the diurnal variations in the quasistatic electric field in the near-Earth atmosphere, fluxes of discrete electromagnetic pulses in the VLF band, source azimuths, narrowband filter output emission intensity at frequencies of 4.65 and 5.3 kHz, and time forms and spectra of VLF pulses have been analyzed. The anomalous behavior of these parameters in October 2002 and August 2004 with different time delay was accompanied by earthquakes near the southeastern coast of Kamchatka at distances of 250–400 km from the registration points. Based on the results of a fine frequency-time analysis of the broadband records of VLF signals, it has been indicated for the first time that discrete electromagnetic pulses observed in anomalous fluxes before earthquakes were signals of local thunderstorm processes.

Power spectra of thermal tidal and planetary waves in the near-Earth atmosphere and in the ionospheric D region at Kamchatka

Spectral analysis of the diurnal variations in the quasi-static electric field in the near-Earth atmosphere and VLF atmospheric radio noise at a frequency of 5.3 kHz, simultaneously observed in September–October 1999 at Paratunka observatory of the Institute of Cosmophysical Research and Radiowave Propagation, has been performed. The variations in the intensities of the spectral power density and the period durations of the variations in the T ∼ 8–24 h band and higher as functions of geomagnetic and seismic activities have been studied.

The thermal decomposition of hexamethylenetetraammonium dodecahydro-closo-dodecaborate

The kinetics and products of the thermal decomposition of hexamethylenetetraammonium dodecahydro-closo-dodecaborate in air, argon, and a vacuum were studied using thermogravimetry, volumetry, mass spectrometry, and IR spectroscopy. According to the nonisothermal kinetic data, noticeable rates of the formation of volatile products were observed at temperatures higher than 150°C. The thermal decomposition of the salt occurred in stages. At 160–200°C, the thermal decomposition of hexamethylenetetraammonium dodecahydro-closo-dodecaborate could not be described by simple kinetic equations. The dependence of the initial reaction rates on inverse temperature (lnV0−1/K) was linear, which showed that the thermal decomposition of the salt obeyed the Arrhenius equation V0 = 109.4 ± 0.6exp[(−20500 ± 1800)/RT], %/min. The obtained temperature dependences of the kinetic parameters of thermolysis were used to predict the time of salt storage and the conditions of work with it. A comparison of the kinetics of the thermolysis of hexamethylenetetraammonium dodecahydro-closo-dodecaborate and free hexamethylenetetraamine in open and closed reaction systems showed that the thermolysis of hexamethylenetetraammonium dodecahydro-closo-dodecaborate was not accompanied by salt dissociation to hexamethylenetetraamine and dodecahydro-closo-dodecaborate acid. The products of its thermolysis volatile under normal conditions were trimethylamine with a small admixture of nitrogen. The solid residue after thermolysis was a high-porosity insoluble product, whose volume was 6–8 times larger than the volume of the initial sample. An analysis of the IR spectra of the solid thermolysis product showed that it had a well-defined salt character. The special features of the IR spectra of initial hexamethylenetetraammonium dodecahydro-closo-dodecaborate and the product of its thermolysis led us to suggest that an acid-base equilibrium of the type [R3N-H+] + A ↔ [R3N… H+…A] occurred in it and, probably, in the initial salt. Here, R3N is the tertiary amino group, and A is the borohydride acid residue. Indications of amorphization allowed us to suggest that polymer structures were formed as a result of intramolecular interaction between the borohydride anion and onium cation.

Appearance of VLF and ELF-noises in topside ionosphere under the action of high power radio wave from data of satellite intercosmos-24☆

Results of a satellite experiment are presented on detection of VLF and ELF-waves excited by irradiation of the night ionosphere F-region by the field of a nonmodulated high-power radio wave. The excited VLF and ELF-waves have been detected at the topside ionosphere heights h=500–1000 km in the frequency bands 8 kHz<f<1.5 kHz and 10 Hz<f<1.5 kHz at distances less than 50–100 km from the centre of the magnetic force tube passing through the heated spot in the ionosphere. The region of wave appearance has well-defined boundaries. This points to propagation (guiding) of the observed low frequency waves along geomagnetic field lines. Possible mechanisms of observed low frequency emission generation are discussed. It is shown that longitudinal ELF-waves may be excited at the heights of topside ionosphere by beams of suprathermal electrons resulting from the action of high-power radio wave on the ionosphere. These waves have a small group velocity in the direction orthogonal to the magnetic field. Whistler waves in the VLF-band may result from conversion of lower-hybrid oscillations excited by the high-power wave into the whistler mode due to scattering by artificial small-scale field-aligned irregularities. The whistlers generated can propagate to the satellite along artificial ducts formed within the disturbed magnetic force tube.

The thermal decomposition of azidopyridines

The thermal decomposition of new heteroaromatic polyazides 2,6-diazido-3,5-dicyanopyridine, 2,4,6-triazido-3,5-dicyanopyridine, and 2,3,4,5-tetraazido-6-cyanopyridine was studied by thermogravimetry, volumetry, mass-spectrometry, and IR spectroscopy. Reaction kinetic parameters were determined. The only gaseous product of the thermal decomposition of all the azides studied was nitrogen, its degree of purity was 99.0–99.8 vol %. 2,6-Diazido-3,5-dicyanopyridine and 2,4,6-triazido-3,5-dicyanopyridine had thermal stability and thermal decomposition parameters close to those of the majority of aromatic azides. The mechanism of thermal decomposition of these azides includes the splitting off of the nitrogen molecule at the initial limiting process stage. Subsequent intermolecular reactions with the participation of nitrenes result in the formation of an amorphous substance containing polyconjugated fragments with sp2 hybridization, which form planar two-dimensional networks. 2,3,4,5-Tetraazido-6-cyanopyridine has very low thermal stability; the rate of nitrogen release during its decomposition is almost 1000 times higher than with 2,6-diazido-3,5-dicyanopyridine and 2,4,6-triazido-3,5-dicyanopyridine at comparable temperatures. This was explained by the presence of the ortho azido group (there is no ortho arrangement of azido groups in 2,6-diazido-3,5-dicyanopyridine and 2,4,6-triazido-3,5-dicyanopyridine).

New hyperbranched poly([1,2,3]-triazole-[1,3,5]-triazines)

New hyperbranched polymers have been synthesized through the 1,3-dipolar polycycloaddition of the AB2 monomer—2-azido-4,6-bis(propynyloxy)-[1,3,5]-triazine. The polymers contain conjugated heteroaromatic triazine and triazole cycles and terminal acetylene groups. The products have been characterized by exclusion liquid chromatography and IR and 1H NMR studies.

On the properties of earthquake precursors in the electrostatic field of the surface atmosphere

The paper presents results of the analysis of occurrence times of earthquake precursors in a quasistatic electric field of the surface atmosphere on the Kamchatka Peninsula. The propagation velocity of the precursors and their occurrence time dependence on the earthquake source depth are estimated. A hypothesis on the possible correlation of the precursor propagation velocity with the diffusion rate of subsurface radon is proposed.

Structures of the Particles of the Condensed Dispersed Phase in Solid Fuel Combustion Products Plasma

The results of experimental investigations of a type of dusty plasma which has been least studied—the plasma of solid fuel combustion products—were presented. Experiments to determine the parameters of the plasma of the combustion products of synthetic solid fuels with various compositions together with simultaneous diagnostics of the degree of ordering of the structures of the particles of the dispersed condensed phase were performed. The measurements showed that the charge composition of the plasma of the solid fuels combustion products depends strongly on the easily ionized alkali-metal impurities which are always present in synthetic fuel in one or another amount. An ordered arrangement of the particles of a condensed dispersed phase in structures that form in a boundary region between the high-temperature and condensation zones was observed for samples of aluminum-coated solid fuels with a low content of alkali-metal impurities.

Spectra of atmospheric waves in the dynamo region of the ionosphere at Kamchatka

A spectral analysis of the diurnal variations in the geomagnetic field horizontal component, observed at Kamchatka and Barrow polar observatory in September–October 1999, has been performed. The complete set of oscillations of thermal tidal atmospheric waves with T = 24, 12, 8, and 4 h has been detected in the variation spectral power (Sq) at Kamchatka, and only the fundamental harmonic with T = 24 h has been distinguished at Barrow. The above periods vary in both directions relative to stable maximums during strong geomagnetic disturbances. The relative spectral intensity at subharmonics also vary toward the fundamental harmonic with a period of 24 h. In the frequency band 0.5–3 h (IGW periods), the maximal intensity in the background spectra is observed at T ∼ 2 h and increases by an order of magnitude with increasing geomagnetic activity at both Kamchatka and Barrow. A day before earthquakes, the intensity of this maximum is below the rms background values, and the spectra widen toward the region of periods shorter than 2 h. A similar effect was previously observed in the power spectra of the diurnal variations in the quasistatic electric field and VLF noise, simultaneously measured in September–October 1999.