# Innovations in applied physics

## Electrodynamical characteristicsof periodic ferromagnetic structures

The periodic structure consisting of a shallow grooves on a surface of a ferromagnetic film was investigated. The electrodynamical characteristics of propagation of the surface magnetostatic wave in this structure were obtained. The 2D model of the periodical Yttrium Iron Garnet structure was numerically studied by the algorithm based on the Finite Element method. The spatial distribution of the electric and magnetic field components in different points of dispersion characteristics was studied in detail.

## Development in spbspu of field emitters for electron devices operating at technical vacuum conditions

The methods of field emitter durability growth while operating in technical vacuum conditions are developed in SPbSPU and are describing in this paper. Two possibilities to secure durable emitter operation are considered: using the special protective fullerene coatings and arrangement of new type of emitter where the fields of spots on the contacts of the materials with greatly different work function provide the field emission.

## The carbon nanotubes grown on molybdenum substratesby cvd-method using thin metal films of iron and water solutions of ferriferous substances as catalysts

The synthesis of carbon nanotubes is carried out on the surface of molybdenum substrates by CVD-method using thin-film iron and water solutions of ferritin and iron acetate as catalysts sources. It is found that the temperature of process technology in the synthesis of carbon nanotubes on molybdenum substrates must be above 900 ◦C. At this point, only non-uniform films of carbon nanotubes on the surface of molybdenum substrates were obtained.

## Study of discrete electron-wave interaction in the passband and stopband of slow-wave systems

This article contains analysis of properties discrete electron-wave interaction in resonance slow-wave system (SWS). Equations of interaction are written in matrix form. Eigenvalues of transfer matrix with electron beam define spread constant of four electron waves. Features of electron waves in SWS with «smooth» energy stream and in SWS with «winding» flow are examined. Simulation is performed and amplification of multisection TWT with passband and stopband sections of SWS is found. Field distribution along stopband section is found.

## An approximate nonlinear theory of double-stream instability

An approximate nonlinear theory of double-stream interaction is built. Based on this theory, calculation for double-stream amplifier gain was performed. It was shown, that 40 dB amplification can be obtained.

## Nonlinear dynamics and chaos in the counterstreaming electron beams with virtual cathodes in vircator without external magnetic field

Virtual cathode nonstationary dynamics has been numerically studied for the two counterstreaming electron beams. The variety of the virtual cathode oscillatory regimes has been discovered from regular to wide band chaotic oscillations. Connection between value of the largest Lyapunov exponent and output signal power has been revealed.

## Dynamics of electron flow with virtual cathode in low-voltage vircator under external force

Theoretical research of dynamics of electron flow with virtual cathode in lowvoltage vircator under external harmonic force has been held in this work. The behavior of electron flow was considered within the framework of both stationary analytic model and numerical simulation of electron flow nonstationary processes. The increasing of lowvoltage vircator output power while increasing external force has been shown in both cases. The results of theoretical research let us to explain physical phenomenon leading to output power increasing.

## Cosmophysical factors in the fluctuations amplitude spectrum of brownian motion

Phenomenon of the regular variability of the fine structure of the fluctuation in the amplitude distributions (shapes of related histograms) for the case of Brownian motion was investigated. We took an advantage of the dynamic light scattering method to get a stochastically fluctuated signal determined by Brownian motion. Shape of the histograms is most likely to vary, synchronous, in two proximally located independent cells containing Brownian particles. The synchronism persists in the cells distant at 2 m from each other, and positioned meridionally.

## Investigation of the broadband noise-like microwave generator on multispeed nonlaminar electron beams

The paper presents the results of theoretical and experimental studies of multispeed electron beams. Theoretical and experimental studies of the structure of such beams are considered. It is shown that turbulence forms in such electron beams. It leads to the formation of multiple bunches of space charge, which are sources of broadband noise-like fluctuations. The results of experimental studies of small-sized laboratory model of the generator based on the principles of formation and use of multispeed turbulent electron beams are shown.

## Analytical consideration of the cosmic factor effects upon the fluctuations of brown particle velocities

Results of analytical consideration of the probability distribution density for Brown particle, subject to weak influence of the external force conditioned by a cosmic particle flow. It is shown that this influence, which is time-dependent, results in essential nonstationarity of the probability distribution, i.e. it becomes a sum of components caused by different astronomical factors: Earth revolution about inherent axes and the Sun, the motion of the Sun and stars and so on.