Characterization of a planar 8 mm wide radiofrequency atmospheric pressure plasma source by spectroscopy techniques

Atmospheric pressure planar radiofrequency (RF) 13.56 MHz discharge in Ar gas generated in a long gap is investigated. The discharge operation with and without a dielectric barrier on the electrodes is studied as a function of the applied power and gas flow. The source afterglow is characterized and is analyzed for possible large-scale biomedical applications where low gas temperature is required. The discharge is studied by relative and absolute emission spectroscopies. A gas temperature as low as 330 +/- 50 K is determined from the rotational-vibrational band of OH emission. The absolute value of the discharge continuum irradiation is used to determine the electron density and the electron temperature. The electron-atom and electron-ion contributions to the bremsstrahlung radiation are calculated and are compared with measured spectra. The electron density of 1.9 +/- 1 x 10(20) m(-3) and electron temperature of 1.75 +/- 0.25 eV are measured in the discharge without a dielectric barrier. It is found that presence of the dielectric has a negligible effect on electron temperature, whereas the electron number density is almost six times lower in the discharge with the dielectric barrier

Crystal structure of mixed fluorites Ca(1-x)Sr(x)F(2) and Sr(1-x)Ba(x)F(2) and luminescence of Eu(2+) in the crystals

Within the framework of the virtual crystal method implemented in the shell model and pair potential approximation the crystal structure of mixed fluorites Ca(1-x)Sr(x)F(2) and Sr(1-x)Ba(x)F(2) has been calculated. The impurity center Eu(2+) and the distance Eu(2+)-F in this crystals have been also calculated. The low level position of excited 4f65d configuration of the Eu(2+) ion has been expressed using phenomenological dependence on distance E(2+)-F. The dependences of Stokes shift and Huang-Rhys factor on concentration x have been received for yellow luminescence in Sr(1-x)Ba(x)F(2):Eu(2+). The value x, for which the eg -level of Eu(2+) ion will be in conduction band in Sr(1-x)Ba(x)F(2):Eu(2+) has been calculated.Comment: 8 pages, 3 figures. The manuscript is sent to journal 'Physics of the solid state'. The results will be submitted on inernational conference SCINTMAT'2002 in oral session (june,20-22,2002,Ekaterinburg,Russia). Corresponding author e-mail: [email protected]

Features of Dynamics of Antivibration Mounts with Inertial Hydraulic Converter Subjected to Vibro-Impact Loading

Antivibration mounts with inertial hydraulic converter are widely used to protect a variety of technical systems from shock and vibration. As it follows from existing literature, models of such a mounts on the basis of mechanical and mechanical-electrical analogies instead of real hydro-mechanical system are usually used to study their dynamic properties and design. These models are not able to describe fluid dynamics in hydraulic mount, and are not suitable to study rapidly changing processes, which is especially required for effective application of the mounts at vibro-shock loading. In this work, a model of inertial hydraulic converter, which is a system of two hydraulic cylinders of unilateral operating principle, connected by a rigid hydraulic tube, is described. Dynamics of fluid in hydraulic converter is described by the Navier-Stokes equations for a compressible fluid and the equation of state of the fluid in assumption of its isentropic motion. The results of numerical simulation of antivibration mount dynamics at shock loading by using finite element package ANSYS/LS-DYNA are presented. It is found out that increasing the length of the tube and reducing the tube diameter lead to an increase in the transmitted dynamic force

Field momentum and gyroscopic dynamics of classical systems with topological defects

The standard relation between the field momentum and the force is generalized for the system with a field singularity: in addition to the regular force, there appear the singular one. This approach is applied to the description of the gyroscopic dynamics of the classical field with topological defects. The collective variable Lagrangian description is considered for gyroscopical systems with account of singularities. Using this method we describe the dynamics of two-dimensional magnetic solitons. We establish a relation between the gyroscopic force and the singular one. An effective Lagrangian description is discussed for the magnetic soliton dynamics.Comment: LaTeX, 19 page

Comment on Vortex Mass and Quantum Tunneling of Vortices

Vortex mass in Fermi superfluids and superconductors and its influence on quantum tunneling of vortices are discussed. The vortex mass is essentially enhanced due to the fermion zero modes in the core of the vortex: the bound states of the Bogoliubov qiasiparticles localized in the core. These bound states form the normal component which is nonzero even in the low temperature limit. In the collisionless regime $\omega_0\tau \gg 1$, the normal component trapped by the vortex is unbound from the normal component in the bulk superfluid/superconductors and adds to the inertial mass of the moving vortex. In the d-wave superconductors, the vortex mass has an additional factor $(B_{c2}/B)^{1/2}$ due to the gap nodes.Comment: 10 pages, no figures, version accepted in JETP Letter

Magnetic vortex as a ground state for micron-scale antiferromagnetic samples

Here we consider micron-sized samples with any axisymmetric body shape and made with a canted antiferromagnet, like hematite or iron borate. We find that its ground state can be a magnetic vortex with a topologically non-trivial distribution of the sublattice magnetization $\vec{l}$ and planar coreless vortex-like structure for the net magnetization $\vec{M}$. For antiferromagnetic samples in the vortex state, in addition to low-frequency modes, we find high-frequency modes with frequencies over the range of hundreds of gigahertz, including a mode localized in a region of radius $\sim$ 30--40 nm near the vortex core.Comment: 20 pages, 1 figur

Trace identities and their semiclassical implications

The compatibility of the semiclassical quantization of area-preserving maps with some exact identities which follow from the unitarity of the quantum evolution operator is discussed. The quantum identities involve relations between traces of powers of the evolution operator. For classically {\it integrable} maps, the semiclassical approximation is shown to be compatible with the trace identities. This is done by the identification of stationary phase manifolds which give the main contributions to the result. The same technique is not applicable for {\it chaotic} maps, and the compatibility of the semiclassical theory in this case remains unsettled. The compatibility of the semiclassical quantization with the trace identities demonstrates the crucial importance of non-diagonal contributions.Comment: LaTeX - IOP styl

Discrete Darboux transformation for discrete polynomials of hypergeometric type

Darboux Transformation, well known in second order differential operator theory, is applied here to the difference equation satisfied by the discrete hypergeometric polynomials(Charlier, Meixner-Krawchuk, Hahn)

Luminescent and dosimetric properties of nanostructured ceramics based on aluminum oxide

The main features of thermoluminescence (TL) of nanostructured ceramics based on anion-defective aluminum oxide have been investigated. The kinetic parameters of the TL dosimetric peak at 475 K have been determined. The possibility of using nanostructured ceramics for beta-radiation dosimetry of high doses (up to 1 kGy) with thermoluminescence of deep traps has been justified. It has been found that the light sum of the dosimetric peak decreases with an increase in the heating rate due to the temperature quenching of the luminescence. The obtained results have confirmed that the mechanism of TL quenching in anion-defective aluminum oxide is associated with the temperature dependence of the probability of the capture in deep traps, which can be caused by thermal ionization of excited states of F-centers. © 2013 Pleiades Publishing, Ltd