ISSN 0869-6632 (Online)
ISSN 2542-1905 (Print)

Innovations in applied physics

Micromagnetic modeling of nonlinear interaction of lateral magnetostatic modes in cross-shaped structures based on waveguides from iron yttrium garnet films

Topic. In this work, parametric processes in the system of predominantly dipole magnetostatic waves (MSW) in the cross-shaped structure from two orthogonal waveguides of iron yttrium garnet film magnetized by the in-plane field H = 460 Oe and having microstrip transducers at its ends are considered. One of the antennas at the end of the transversely

Zones of stable single-mode generation in overmoded gyrotrons

During numerical simulations of the model of gyrotron with ?xed ?eld-structure, zones of stable single-mode generation of the work mode are analyzed on the plane of parameters «magnetic ?eld – beam current». It is shown that area and sizes of the zones are strongly dependent on the spectral density of eigen-frequencies of the resonator and on number of considered parasit modes. With increase of spectral density the point of highest attainable e?ciency of stable single-mode generation shifts to the region of lower currents and simultaneously this value of e?ciency decreases.

Electrodynamical characteristicsof periodic ferromagnetic structures

The periodic structure consisting of a shallow grooves on a surface of a ferromagnetic ?lm 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 ?eld components in di?erent points of dispersion characteristics was studied in detail. The comparison of experimental data and numerical results was carried out.

Methods of output power increasing in orotron with double- row periodic structure in the short-wavelength part of millimeter-wave range

The peculiarities of the orotron double-row electrodynamical system and methods of output power increase were investigated. For the ?rst time in the experimental model of orotron with electrodynamical system consisting of double-row plain periodic structure (DRPS) and sphere-cylindrical focusing mirror the possibility of using wide electron beam in order to output power increase in 140...300 GHz frequency range is demonstrated.

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

The methods of ?eld 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 ?elds of spots on the contacts of the materials with greatly di?erent work function provide the ?eld 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-?lm 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 ?lms 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 de?ne spread constant of four electron waves. Features of electron waves in SWS with «smooth» energy stream and in SWS with «winding» ?ow are examined. Simulation is performed and ampli?cation 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 ampli?er gain was performed. It was shown, that 40 dB ampli?cation 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 ?ow with virtual cathode in lowvoltage vircator under external harmonic force has been held in this work. The behavior of electron ?ow was considered within the framework of both stationary analytic model and numerical simulation of electron ?ow 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.