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L. I. Ognev

Publications and source records attributed to L. I. Ognev.

7 recordsLinked to original sources
arXiv2008

Optimization of compact Soller collimator

The opportunity of optimization of collimator was investigated by changing collimator length, material and wall roughness for soft x-ray radiation with wavelength 4 nm corresponding to carbon atoms absorption. From the obtained results follows that effects of diffraction become significant for channel widths up to 0.02 - 0.04 mm. Collimation angle was limited to 0.014 and 0.007 radian for carbon dust detection. The choice of lighter material with greater height of roughness in shorter collimator with 2 reflections results in considerably lower losses than for heavier materials and smoother walls where 4 reflections required.

physics.optics↗
arXiv2006

Temperature bistability of charged dust particle in plasma

By computer numerical simulation of heating of a dust conducting particle in homogeneous plasma it was shown that depending on initial temperature of a particle both heating and cooling were possible with formation of two different quasi-stable conditions - temperature bistability. The "hot" condition corresponds to positive charge of the particle and "cold" condition corresponds to negative charge. The stability of the "cold" state is provided by radiation losses. The method of experimental observation of the effect was proposed.

physics.optics↗
arXiv2005

Thermal radiation of conducting nanoparticles

The thermal radiation of small conducting particles was investigated in the region where the Stephan-Boltzmann law is not valid and strongly overestimates radiation losses. The new criterion for the particle size, at which black body radiation law fails, was formulated. The approach is based on the magnetic particle polarization, which is valid until very small sizes (cluster size) where due to drop of particle conductivity the electric polarization prevails over the magnetic one. It was also shown that the radiation power of clusters, estimated on the basis of the experimental data, is lower than that given by the Stephan-Boltzmann law.

physics.optics↗
arXiv2004

Kinoform refraction lens with diffraction calculation

By direct numerical simulations of the kinoform refractive lens within the quazioptical approach the effects of shape misalinement were investigated. The quazioptical approach was based on numerical integration of parabolic equation for complex wave amplitude by spep-by-step method with "splitting" procedure. The effect of 2pi- shift compensation was calculated for different orders and imperfections. The performance of kinoform lens was compared with the compound refractive lens and thin lens approximation.

physics.optics↗
arXiv1998

Wave channeling of X-rays in narrow rough capillaries - non Andronov-Leontovich theory

The effect of capture of X-ray beam into narrow submicron capillary was investigated with account for diffraction and decay of coherency by roughness scattering in transitional boundary layer. In contrast to well-known Andronov-Leontovich approach the losses do not vanish at zero gliding angle and scale proportional to the first power of roughness amplitude for small gliding angles. It was shown that for small correlation radius of roughness the scattering decay of coherency can be made of the same order as absorption decay of lower channeling modes to produce angular collimation of X-ray beams. Estimates were given for optimum capillary length at different roughness amplitudes for angular sensitivity of X-ray transmission and chenneling effects that can be usefull for designing of detector systems.

physics.optics↗
arXiv1998

Numerical simulation of gliding reflection of X-ray beam from rough surface

A new method for investigation of x-ray propagation in a rough narrow dielectric waveguide is proposed on the basis of the numerical integration of the quazioptical equation. In calculations a model rough surface was used with the given statistical properties. It was shown that the losses in the narrow waveguides strongly depend on the wall roughness and on the input angle. The losses are not zero even at zero input angle if the width of the waveguide is smaller or about 1 mkm. The effect is accounted for as the influence of diffraction. The angular spread of the transmitted X-ray radiation is much more narrow than the Fresnel angle of the total external reflection.

physics.optics↗