Periodic motions (close to stationary) of an axisymmetric satellite with magnetic damping

Close to stationary periodic motions of an axisymmetric satellite in a circular orbit are considered. The satellite was equipped with a spherical magnetic damper. The investigation was conducted on the assumption that a strong magnet was installed on the damper float. Stationary rotations of the satellite around the axis of symmetry are selected as the generating solutions. The solutions are constructed in the form of power series of the smaller parameter, and they are extended numerically to the region of random values of the damping coefficient. The stability of the resulting solutions was investigated

Instabilities of the normal state in current-biased narrow superconducting strips

We study the current-voltage characteristic of narrow superconducting strips in the gapless regime near the critical temperature in the framework of the Ginzburg-Landau model. Our focus is on its instabilities occurring at high current biases. The latter are consequences of dynamical states with periodic phase-slip events in space and time. We analyze their structure and derive the value of the reentrance current at the onset of the instability of the normal state. It is expressed in terms of the kinetic coefficient of the time-dependent Ginzburg-Landau equation and calculated numerically

Broken space-time symmetries and mechanisms of rectification of ac fields by nonlinear (non)adiabatic response

We consider low-dimensional dynamical systems exposed to a heat bath and to additional ac fields. The presence of these ac fields may lead to a breaking of certain spatial or temporal symmetries which in turn cause nonzero averages of relevant observables. Nonlinear (non)adiabatic response is employed to explain the effect. We consider a case of a particle in a periodic potential as an example and discuss the relevant symmetry breakings and the mechanisms of rectification of the current in such a system.Comment: 11 pages, 10 figure

Revivals and oscillations of the momentum of light in a planar multimode waveguide

The evolution of the transverse momentum of monochromatic light entering a multimode planar waveguide at large angle is investigated. We report on oscillations of the momentum caused by the beatings between the adjacent populated modes of the waveguide and their periodic collapses and revivals. A new type of an interferometer based on this effect with fringe spacing as small as 1/9 of a light wavelength is demonstrated experimentally and periods as small as 1/1000 of a light wavelength seem to be feasible

A multi-channel wire gas electron multiplier

A novel and relatively simple method of production of electrodes for a multi-channel wire gas multiplier is developed. Two modifications of the multipliers have been tested: with a multiplication of electrons between two wire electrodes, MWGEM, and between a wire electrode and continuous anode, MWCAT. For both MWGEM and MWCAT detectors, filled with neon under pressure of 760 Torr and irradiated by beta-particles (Ni-63), the coefficient of proportional multiplication of electrons up to 10000 was obtained. For the MWGEM detector irradiated by alpha-particles (Pu-239), the coefficient of proportional multiplication of 300 was obtained. It is observed, that in contrast to the GEM detectors, produced by perforation of a metal-clad plastic foil, in a MWGEM the discharges do not destroy its electrodes even for the potentials above the threshold of discharges. The results on operation of the MWCAT filled with Ar, Ar+CH4 and Ar+1% Xe are also presented.Comment: 4 pages, 9 figure

Influence of spin structures and nesting on Fermi surface and a pseudogap anisotropy in t-t'-U Hubbard model

Influence of two type of spin structures on the form of the Fermi surface (FS) and a photoemission intensity map is studied for t-t'-U Hubbard model. Mean field calculations are done for the stripe phase and for the spiral spin structure. It is shown, that unlike a case of electron doping, the hole-doped models are unstable with respect to formation of such structures. The pseudogap anisotropies are different for h- and e- doping. In accordance with ARPES data for La2SrxCuO4 the stripe phase is characterized by quasi-one-dimensional segments of FS at k=(\pi,0) and by suppression of spectral weight in diagonal direction. It is shown that spiral structures display the polarisation anisotropy: different segments of FS correspond to electros with different spin polarisations.Comment: 12 pages, 4 figure

Bose-Einstein condensation of semi-hard bosons in S=1 dimerized organic compound F2PNNNO

An analysis of the energy spectrum and the magnetization curve of two-dimensional organic antiferromagnet F2PNNNO with a spin-one dimerized structure shows that a behavior of the compound in an external magnetic field can be explained within a lattice boson model with an extended Pauli's exclusion principle, i.e. no more than two bosons per a dimer. The unusual magnetization curve observed experimentally in the compound reflects a sequence of phase transitions intrinsic for a lattice boson system with strong on-site and inter-site repulsions due to a tuning of magnon density by the applied magnetic field

Theory of standing spin waves in finite-size chiral spin soliton lattice

We present a theory of standing spin wave (SSW) in a monoaxial chiral helimagnet. Motivated by experimental findings on the magnetic field-dependence of the resonance frequency in thin films of Cr${}$Nb$_{3}$S${}_{6}$[Goncalves et al., Phys. Rev. B95, 104415 (2017)], we examine the SSW over a chiral soliton lattice (CSL) excited by an ac magnetic field applied parallel and perpendicular to the chiral axis. For this purpose, we generalize Kittel-Pincus theories of the SSW in ferromagnetic thin films to the case of non-collinear helimagnet with the surface end spins which are softly pinned by an anisotropy field. Consequently, we found there appear two types of modes. One is a Pincus mode which is composed of a long-period Bloch wave and a short-period ripple originated from the periodic structure of the CSL. Another is a short-period Kittel ripple excited by space-periodic perturbation which exists only in the case where the ac field is applied perpendicular the chiral axis. We demonstrate that the existence of the Pincus mode and the Kittel ripple is consistent with experimentally found double resonance profile.Comment: 17 pages, 14 figure

Strong pair correlation in small metallic nanoclusters: the energy spectrum

The electronic shell structure in small metallic nanoclusters leads to high level degeneracy, which is strongly beneficial for the appearance of pair correlation. This results in a high value of Tc as well as in the appearance of a superconducting gap which causes a strong modification of the energy spectrum. The electronic energy spectrum becomes strongly temperature dependent. Consequently, specific experiments to demonstrate the presence of pair correlation can be proposed

Short-distance atomic beam deceleration with a stimulated light force.

We have decelerated a cesium atomic beam from thermal velocities down to several tens of m/s within only a 10 cm slowing distance. A bichromatic standing light wave was used to generate a stimulated force exceeding the spontaneous force limit by a factor of ∼10 and extending over a large, saturation-broadened velocity range. Because of the short slowing distance this method allows production of very intense, continuous beams of slow atoms