Dynamic stabilization of non-spherical bodies against unlimited collapse

We solve equations, describing in a simplified way the newtonian dynamics of a selfgravitating nonrotating spheroidal body after loss of stability. We find that contraction to a singularity happens only in a pure spherical collapse, and deviations from the spherical symmetry stop the contraction by the stabilising action of nonlinear nonspherical oscillations. A real collapse happens after damping of the oscillations due to energy losses, shock wave formation or viscosity. Detailed analysis of the nonlinear oscillations is performed using a Poincar\'{e} map construction. Regions of regular and chaotic oscillations are localized on this map.Comment: MNRAS, accepted, 7 pages, 9 figure

Pressurized rf cavities in ionizing beams

A muon collider or Higgs factory requires significant reduction of the six dimensional emittance of the beam prior to acceleration. One method to accomplish this involves building a cooling channel using high pressure gas filled radio frequency cavities. The performance of such a cavity when subjected to an intense particle beam must be investigated before this technology can be validated. To this end, a high pressure gas filled radio frequency (rf) test cell was built and placed in a 400 MeV beam line from the Fermilab linac to study the plasma evolution and its effect on the cavity. Hydrogen, deuterium, helium and nitrogen gases were studied. Additionally, sulfur hexafluoride and dry air were used as dopants to aid in the removal of plasma electrons. Measurements were made using a variety of beam intensities, gas pressures, dopant concentrations, and cavity rf electric fields, both with and without a 3 T external solenoidal magnetic field. Energy dissipation per electron-ion pair, electron-ion recombination rates, ion-ion recombination rates, and electron attachment times to SF6 and O-2 were measured.ope

Formation principles of layers from active carbon microparticles with grafted amine derivatives of PVC on substrate

Porous layers from activated carbon with macro-molecular cyclic amines based on PVC and modyfied by primary amines were synthesized and its properties were described. Layers were grafted to the surface of a PVC film, cotton medical gauze and asbestos fabric. The nature of benzyl alcohol solvatation and the mechanism of suspension formation within layers of macro-molecular cyclic amines were investigated by methods of IR-spectroscopy and luminescence spectroscopy and described. The structural features of grafted PVC was identified and the influence of the substrate nature on the structure was traced. Upon contact of particles with benzyl alcohol molecules from solvatocomplexes PVC-related aromatic groups replace benzyl alcohol in solvatocomplexes. This leads to non-covalent binding of groups on the surface of the particles. It was shown that sorption of organic molecules does not affect the number of structural types of oxoamines

Layers of active carbon with grafted sodium and potassium glycinate derivatives on the surface of PVC film

Porous layers from active carbon with macro-molecular cyclic amines with sodium or potassium acetate substituents were synthesized. Layers sewn to the surface of a film of PVC. It is shown that the graft zones around carbon particles consist of luminophore groupings in the form of conjugated rings, including radicals with substituted amino groups, conjugated carbon groups and oxygen atoms binding these groups. The electronic conductivity of the layers and their sorption capacity for the absorption of benzene vapor are measured. It is established that the conductivity of the layer is the higher, the smaller the PVC derivatives, the carbon particles are combined. The conductivity of the layers with potassium ions is greater than that of sodium ions. It is assumed that most of the vapors are concentrated in the pores in the carbon. The sorption capacity of layers with sodium ions is greater than that of potassium ions

On the Possibility of Development of the Explosion Instability in a Two-Component Gravitating System

We obtain an expression for the energy of the density wave propagating in a multicomponent gravitating medium in the form well known from electrodynamics. Using the above, the possibility of "triple production" of the quasi-particles, or waves, with their energies summing up to zero, in a non-equilibrium medium is demonstrated. That kind of resonance wave interaction is shown to result in the development of an explosion instability. By the method developed in plasma physics, the characteristic time of the instability is evaluated.Comment: 15 pages, 3 figures, accepted for publication (JETP

Inner Polar Rings and Disks: Observed Properties

A list of galaxies with inner regions revealing polar (or strongly inclined to the main galactic plane) disks and rings is compiled from the literature data. The list contains 47 galaxies of all morphological types, from E to Irr. We consider the statistics of the parameters of polar structures known from observations. The radii of the majority of them do not exceed 1.5 kpc. The polar structures are equally common in barred and unbarred galaxies. At the same time, if a galaxy has a bar (or a triaxial bulge), this leads to the polar disk stabilization - its axis of rotation usually coincides with the major axis of the bar. More than two thirds of all considered galaxies reveal one or another sign of recent interaction or merging. This fact indicates a direct relation between the external environment and the presence of an inner polar structure.Comment: 12 pages, 3 figures, accepted to Astrophysical Bulletin. Minor changes and corrections are still possibl