Structural and radiation color centers and the dielectric properties of doped yttrium aluminum garnet crystals

The results of experimental and theoretical studies of the spectral and dielectric properties of garnet Y₃Al₅O₁₂ crystals are analyzed. The crystals studied were grown under different conditions and were either pure or contained iron-group ion impurities (Ti, Cr, Fe). The crystals were studied before and after irradiation by γ rays and high-energy electrons. A model is proposed for the formation of color centers and their influence on luminescent and other optical and dielectric properties.     

Experiments on the formation of an intense helical electron beam under conditions of picking-up of the electrons reflected from the magnetic mirror

We propose a method of increasing the pitch factor and decreasing the spread of rotational velocities of helical electron beams (HEBs) formed in nonadiabatic magnetron-injection guns of gyroresonant devices. The method is based on the effect of a special diaphragm mounted at the starting point of the transport channel on the process of formation of the laminar electron beam. The diaphragm located at one of the trajectory minima has such a diameter that it cannot be bent around by electrons with minimum rotational velocities. Such electrons land on it, whereas the remaining electrons pass further, moving in an increasing magnetic field. Then the electrons with the maximum rotational velocities reflect from the magnetic mirror adiabatically and land on the other side of the same diaphragm. Thus, the electron beam in the cavity contains electrons with a smaller resulting spread of rotational velocities. In the region of the HEB formation, the accumulation of the space charge of reflected electrons is eliminated, and the shielding of the electric field at the cathode is reduced, which eventually leads to an increase in the HEB pitch factor. Using such a diaphragm in the regime of current limitation by the space charge, the HEB with a high pitch factor (about 1.4) and a velocity spread acceptable for gyrotron applications (lower than 30%) was formed. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 9, pp. 785–792, September 2007.     

Observation of chaotic dynamics in a powerful backward-wave oscillator

Self-modulation regimes of generation in a powerful 10-micros X-band backward-wave oscillator were studied theoretically and experimentally. The sequence of the self-modulation patterns and corresponding bifurcation values observed as the current was increased were in good agreement with the results of simulations. It was found that at a current of 120 A chaotic self-modulation set in at a power of 2 MW and a relative spectral width of 4%.     

Herstellung und Eigenschaften der N-substituierten Polyamide

Ohne Zusammenfassung     

Experiments on breaking cast iron blocks with dynamic loading

Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 1, pp. 121–123, Janaury–February, 1992.     

Dynamical systems in the theory of solitons in the presence of nonlocal interactions

The behavior of solitons in models which take into account complex dispersion or nonlocal interaction of nonlinear waves is examined. A method is proposed to reduce this problem to one involving special trajectories (homoclinic and heteroclinic) of the dynamic system. This method involves replacing the nonlinear integrodifferential equation with the differential equations which link the original nonlinear field with the auxiliary linear fields. The interaction of fields in such a model is a local interaction. The number of introduced linear fields is determined by the Laplace transform of the integral operator kernel of the basic integrodifferential equation. The problem involving topological solitons for the nonlocal generalization of the Klein-Gordon equation is considered. Nonlocal interactions are found to lead to a number of singularities (unrestricted increase in the slope of the topological soliton front, break in the solutions, and other singularities).