An exact solution to the nonlinear kinetic equation is used to examine the limiting states arising in a slow-wave system with beam generation of harmonic waves. The limiting current for single-mode generation is estimated. Efficient energy transfer from the beam to the wave is possible only for a relativistic beam in a slow-wave system. The choice of optimal parameters is discussed for generating waves in a specified wavelength range.
Show AbstractMeasurements have been made on the motion of a shock wave in a hot gas at constant pressure; differential relationships have been derived for the one-dimensional motion in a perfect gas in which the temperature and velocity are dependent on a coordinate; other results have been obtained for a gas mixture having a distribution of the component concentrations at constant pressure and temperature. Formulas are given for the time derivative of the Mach number of the wave and the derivative of the density with respect to the coordinate in the gas behind the wave for the instant when the wave encounters the boundary of the nonuniformity. Results are given from numerical calculations on the passage of a shock wave through a gas with a negative density gradient at constant pressure. The theoretical values for the change in shock-wave speed are compared with the measured ones.
Show AbstractResults are presented on bottom density flows under natural conditions; vertical distributions have been derived for the density, turbidity, mean velocity, scale of the fluctuations in the two flow-speed components, and the turbulent frictional stress. It is concluded that the mechanism of the flow near the bottom is similar to the mechanism for the liquid boundary of the bottom density flow. Although the results are in qualitative agreement with published data, there are substantial quantitative discrepancies over the major turbulent characteristics.
Show AbstractMeasurements have been made on the interaction of a shock wave with a vortex ring at M of 1.1-3; the velocity of the ring with respect to the gas is reduced after passage through the shock wave. Also, the vortex ring is disrupted at speeds in excess of 160 m/sec.
Show AbstractThe effects of compound states of 2p2h type have been examined for giant dipole resonances having T< and T> in and 60^Ni, 90^Zr,208^Pb; calculations have been performed on the structure of the giant resonances (T< and T>) and on the energy spectra of the photonucleons.
Show AbstractShock-wave shapes are considered for a medium without dispersion whose nonlinearity can be approximated by a piecewise-linear function; recordings have been made of the distortion of a sine wave in a line of low-pass filter type containing MIS varicaps operating at various bias levels.
Show AbstractAnalytical and numerical solutions are given for the effects of nuclear volume on the positions of the electronic levels.
Show AbstractThe finite-element method is applied to the free and forced oscillations of a shell in a liquid; the matrix equation is derived for the pressure of the liquid on the shell, in which a polynomial of first degree is used to approximate the density of the simple sources at the surface of the shell. A numerical calculation is presented for a particular shell, and the resonant frequencies of the shell in a liquid are determined.
Show AbstractAn expression is derived for the intensity of the emission from a uniformly moving charge when there is a double discontinuity in the dielectric constant of the medium; limiting cases are examined.
Show AbstractAn equation chain has been solved for correlation functions on the basis that the correlation integrals are small; the first approximation is obtained for a homogeneous system. The result is the same as the expression derived by Bogolyubov by expanding the distributions as series in terms of a small parameter, while for a crystal it is the same as the analogous expression for the binary distribution.
Show AbstractA relationship is considered between the NMR line positions and the relative signs of the spin-spin interaction parameters; spectra from three groups of equivalent nuclei are used to derive the general rules for determining the signs ABC spectra are especially considered. The method can be generalized to a system with a large number of groups of equivalent nuclei.
Show AbstractSome basic quantities in nonequilibrium thermodynamics are generalized to discuss relaxation processes in a mixture of a diatomic gas with a light inert gas having a substantially nonmaxwellian distribution for the light particles. Also, theorems from nonequilibrium thermodynamics are generalized to stationary states. The general case of a stationary state without minimal generalized entropy production is considered, along with stationary states for which the generalized entropy production is minimal.
Show AbstractSimple expressions have been derived for the reflection coefficient, absorption, and phase shift of a quarter-wave dielectric mirror, which incorporate the absorption in the films; features of the mirror implied by the formulas are discussed.
Show AbstractCurrent relaxation and the frequency dependence of the jump conduction have been examined via percolation arguments and hypothesis on the behavior of the correlation length near the threshold corresponding to the formation of an infinite bond cluster. It is shown that the relaxation at large times and the frequency dependence of the conduction over a wide frequency range are governed by a universal function that is the solution to a transcendental equation whose only parameter is a critical value. This function is of power-law type over a restricted frequency range, and the exponent varies between 0.5 and 1.
Show AbstractA study has been made of methods of stabilizing the output intensity at 253.7 nm from an electrodeless high-frequency discharge in mercury vapor. The intensity distribution in the spectrum varies with the temperature of the sidearm and the input power; working temperature ranges have been defined to provide maximum stability for discharges of the first and second kinds. A stabilizer has been built that provides an intensity stability of about 1% over a period of 2 hr without thermal stabilization of the sidearm.
Show AbstractThe Landau problem is considered for an initial perturbation in a relativistic plasma, with correction for radiation retardation. The damping due to the latter factor exceeds the Landau damping for the waves in a plasma of concentration $10^9—10^14 cm^{-3}$ if the phase velocity is substantially larger than the electron thermal velocity.
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