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121.
122.
L. P. Babich 《Journal of Experimental and Theoretical Physics》2004,98(4):707-718
The collision operator of relativistic electrons with a cold gas of atomic particles is derived consistently taking into account elastic interactions, excitation of electron shells, and ionization. The creation of secondary electrons is described accurately. In the range of energies exceeding the binding energy of atomic electrons, the operator implicates only the angular scattering by nuclei and the ionization integral that automatically allows for scattering by atomic electrons. The collision operator used earlier for studying the kinetics of avalanches of relativistic runaway electrons is analyzed. A more exact operator derived in the present study is simpler in form and saves time in computer calculations. 相似文献
123.
V. V. Alexandrov E. V. Grabovsky M. V. Zurin I. V. Krasovsky K. N. Mitrofanov S. L. Nedoseev G. M. Oleinik I. Yu. Porofeev A. A. Samokhin P. V. Sasorov V. P. Smirnov M. V. Fedulov I. N. Frolov 《Journal of Experimental and Theoretical Physics》2004,99(6):1150-1172
A qualitative model of the dynamics of a multiterawatt radiating Z-pinch with cold start and high rate of current rise is proposed. The model is used to analyze discharges with currents I ~ 2–5 MA (with dI/dt > 1013 A/s) through uniform or structured plasma-producing loads, including wire arrays. The most important consequence of cold start is that spatially nonuniform plasma production is prolonged to almost the entire current rise time. Under these conditions, the Ampére force begins to play a dominant role in the plasma dynamics before the plasma-producing load is completely transformed into an accelerated plasma. The results of computations of wire-array vaporization are presented. A formula is proposed for estimating the highest attainable velocity of plasma flow into a heterogeneous liner driven by the Ampére force. It is shown that local imbalance between radial motion of the produced plasma and supply of the plasma-producing substance to be ionized leads to axially nonuniform breakthrough of magnetic flux into the liner, which precedes plasma collapse. The magnetic-flux breakthrough gives rise to a chaotic azimuthal-axial plasma structure consisting of radial plasma jets of relatively small diameter, which is called a radial plasma rainstorm. The breaking-through azimuthal magnetic flux obstructs further current flow in the breakthrough region. Analyses of Z-pinch implosion based on the theory of Rayleigh-Taylor instability or the snowplow model are incorrect under the plasma-rainstorm conditions. The processes taking place in a stagnant Z-pinch include conversion of the energy carried by the current-generated magnetic field into turbulent MHD flow of the ion component of the plasma, its convective mixing with magnetic field, heating, energy transfer from ions to electrons, and emission from the plasma. Under typical experimental conditions, emission plays a key role in the energy balance in an imploding pinch. Z-pinch is modeled by an electric-circuit component that has a time-dependent nonlinear impedance and consumes the magnetic energy supplied by a generator through a magnetically insulated transmission line (MITL). The peak power reached in the circuit is comparable to the peak soft X-ray power output emitted by the pinch in terms of magnitude and timing. Optimum matching conditions are formulated for the generator-MITL-pinch circuit. 相似文献
124.
Yu. B. Bolkhovityanov S. Ts. Krivoshchapov A. I. Nikiforov B. Z. Ol’shanetskii O. P. Pchelyakov L. V. Sokolov S. A. Teys 《Physics of the Solid State》2004,46(1):64-66
Different techniques for the fabrication of structures containing ensembles of ultrasmall germanium nanoclusters distributed with a high density over the substrate surface are discussed. How to control the morphology and ordering of these ensembles is also discussed. 相似文献
125.
B. P. Sorokin D. A. Glushkov L. N. Bezmaternykh V. L. Temerov I. A. Gudim K. S. Aleksandrov 《Physics of the Solid State》2004,46(3):458-461
Single crystals of lead gallium germanate Pb3Ga2Ge4O14 are grown from their own solution melts. The propagation of bulk acoustic waves is investigated, and the elastic, piezoelectric, and dielectric constants are calculated. The temperature dependences of the dielectric constants of this compound are analyzed. 相似文献
126.
E. A. Ekimov E. L. Gromnitskaya D. A. Mazalov A. F. Pal’ V. V. Pichugin S. Gierlotka B. Palosz J. A. Kozubowski 《Physics of the Solid State》2004,46(4):755-757
Superhard nanodiamond-SiC ceramics are prepared by infiltrating liquid Si into porous nanodiamond compacts under pressure.
Synthesized samples are 2.2 mm thick and 3–4 mm in diameter. The effect of particle size of dynamically synthesized nanodiamond
powders on silicon infiltration and SiC phase formation is studied. It is established that silicon does not penetrate into
the pores of nanodiamond powders if the original particle size is smaller than 0.5–1.0 μm. The critical pore size for infiltration
is 100–200 nm. A study of the microstructure of the samples showed the presence of the nanometer-and submicron-scale SiC phase.
The ultrasound velocities are measured in the prepared compacts, and the elastic moduli are calculated.
__________
Translated from Fizika Tverdogo Tela, Vol. 46, No. 4, 2004, pp. 734–736.
Original Russian Text Copyright ? 2004 by Ekimov, Gromnitskaya, Mazalov, Pal’, Pichugin, Gierlotka, Palosz, Kozubowski. 相似文献
127.
Technical Physics - Analytical models for the magnetization vector field B m in a uniaxial ferromagnetic film are studied. Some of them are found to closely approximate B m even if the quality... 相似文献
128.
E. L. Pankratov 《Technical Physics》2004,49(1):114-118
The establishment of the steady-state dopant profile in a medium with a time-variable diffusion coefficient is considered
within the approach proposed previously for estimating mass-and heat-transfer time characteristics. It is shown that the time
it takes for the equilibrium concentration to set in may be increased or decreased by appropriately choosing the law of variation
of the diffusion coefficient. 相似文献
129.
Oksengendler B. L. Karimov M. Yunusov M. C. Karakhodzhaev A. K. 《Russian Physics Journal》2004,47(7):790-791
Russian Physics Journal - 相似文献
130.
L. A. Manakova 《Journal of Experimental and Theoretical Physics》2004,99(1):157-168
The mechanisms leading to instability of the non-Fermi-liquid state of a Luttinger liquid with two-level impurities are proposed. Since exchange scattering in 1D systems is two-channel scattering in a certain range of parameters, several types of non-Fermi-liquid excitations with different quantum numbers exist in the vicinity of the Fermi level. These excitations include, first, charge density fluctuations in the Luttinger liquid and, second, many-particle excitations due to two-channel exchange interaction, which are associated with band-type as well as impurity fermion states. It is shown that mutual scattering of many-particle excitations of various types leads to the emergence of an additional Fermi-liquid singularity in the vicinity of the Fermi level. The conditions under which the Fermi-liquid state with a new energy scale (which is much smaller than the Kondo temperature) is the ground state of the system are formulated. 相似文献