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We discuss here the direct and inverse problems for wave propagation in a waveguide with rough internal surface and arbitrary mean shape. The high degree of multiple scattering inside the waveguide poses significant challenges both for the…

Computational Physics · Physics 2024-06-14 Mark Spivack , Orsola Rath Spivack

This paper presents a new method to model X-ray scattering on random rough surfaces. It combines the approaches we presented in two previous papers -- \zs\cite{zhao03} \& \pz\cite{zhao15}. An actual rough surface is (incompletely) described…

Classical Physics · Physics 2017-04-13 Ping Zhao

To take advantage of high-resolution optics sensitive to a broad energy range, future X-ray imaging instruments will require thick detectors with small pixels. This pixel aspect ratio affects spectral response in the soft X-ray band, vital…

The boundaries of waveguides and nanowires have drastic influence on their coherent scattering properties. Designing the boundary profile is thus a promising approach for transmission and band-gap engineering with many applications. By…

Mesoscale and Nanoscale Physics · Physics 2012-12-04 O. Dietz , H. -J. Stöckmann , U. Kuhl , F. M. Izrailev , N. M. Makarov , J. Doppler , F. Libisch , S. Rotter

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…

Optics · Physics 2007-05-23 L. I. Ognev

Sheets of slab waveguides with sharp corners are investigated. By means of rigorous numerical experiments, we look at oblique incidence of semi-guided plane waves. Radiation losses vanish beyond a certain critical angle of incidence. One…

Optics · Physics 2016-04-20 Manfred Hammer , Andre Hildebrandt , Jens Förstner

The reflection and transmission amplitudes of waves in disordered multimode waveguides are studied by means of numerical simulations based on the invariant embedding equations. In particular, we analyze the influence of surface-type…

Disordered Systems and Neural Networks · Physics 2009-10-31 J. A. Sanchez-Gil , V. Freilikher , A. A. Maradudin , I. Yurkevich

We give a detailed analysis of long range cumulative scattering effects from rough boundaries in waveguides. We assume small random fluctuations of the boundaries and obtain a quantitative statistical description of the wave field. The…

Analysis of PDEs · Mathematics 2011-11-07 Ricardo Alonso , Liliana Borcea , Josselin Garnier

We use the parabolic wave equation to study the propagation of x-rays in tapered waveguides by numercial simulation and optimization. The goal of the study is to elucidate how beam concentration can be best achieved in x-ray optical…

Materials Science · Physics 2009-11-13 Sebastian Panknin , Alexander K. Hartmann , Tim Salditt

The problem of diffraction of a waveguide mode by a thin Neumann screen is considered. The incident mode is assumed to have frequency close to the cut-off. The problem is reduced to a propagation problem on a branched surface and then is…

Analysis of PDEs · Mathematics 2015-12-24 Andrey V. Shanin , Andrey I. Korolkov

A formalism is introduced for the non-perturbative, purely numerical, solution of the reduced Rayleigh equation for the scattering of light from two-dimensional penetrable rough surfaces. As an example, we apply this formalism to study the…

Optics · Physics 2012-05-03 Tor Nordam , Paul Anton Letnes , Ingve Simonsen

When a plane electromagnetic wave impinges upon a diffraction grating or other periodic structures, reflected and transmitted waves propagate away from the structure in different radiation channels. A diffraction anomaly occurs when the…

Computational Physics · Physics 2022-10-05 Zitao Mai , Ya Yan Lu

Diffraction of a surface wave on a rectangular wedge with impedance faces is studied using the Sommerfeld-Malyuzhinets technique. An analog of Landau's bypass rule in the theory of plasma waves is introduced for selection of a correct…

Optics · Physics 2014-03-25 Igor A. Kotelnikov , Vasily V. Gerasimov , Boris A. Knyazev

The question on X-ray extreme focusing (smallest reachable spot size) brings us to the idea for using the wave features of X-ray propagation in media. As known, wave features are revealed at propagation in ultra-narrow collimators as well…

Optics · Physics 2009-11-13 S. B. Dabagov

The theoretical formulation of x-ray resonant magnetic scattering from rough surfaces and interfaces is given for specular reflectivity. A general expression is derived for both structurally and magnetically rough interfaces in the…

Materials Science · Physics 2009-11-10 D. R. Lee , D. Haskel , Y. Choi , J. C. Lang , S. A. Stepanov , G. Srajer , S. K. Sinha

In the linear approximation, we study a one-dimensional problem of the reflectionless wave propagation on a surface of a shallow duct with the spatially varying water depth, duct width, and current. We show that both global and bounded…

Fluid Dynamics · Physics 2021-12-08 Semyon Churilov , Yury Stepanyants

Free-space propagation can be described as a shearing of the Wigner distribution function in the spatial coordinate; this shearing is linear in paraxial approximation but assumes a more complex shape for wide-angle propagation. Integration…

Optics · Physics 2009-11-10 J. B. Almeida , V. Lakshminarayanan

Conventional X-ray methods use incoming plane waves and result in discrete diffraction patterns when scattered at crystals. Here we find, by a systematic method, incoming waveforms which exhibit discrete diffraction patterns when scattered…

Optics · Physics 2015-06-16 Gero Friesecke , Richard D. James , Dominik Jüstel

Geometrically decorated two-dimensional (2D) discrete surfaces can be more effective than conventional smooth reflectors in managing wave radiation. Constructive non-specular wave scattering permits the scattering angle to be other than…

At millimeter-wave frequencies, diffuse scattering from rough surfaces is an important propagation mechanism. Including this mechanism in radio propagation modeling tools,such as ray-tracing, is a key step towards realizing accurate…

Signal Processing · Electrical Eng. & Systems 2021-06-16 Stefanos Bakirtzis , Takahiro Hashimoto , Costas D. Sarris
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