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Dynamical diffraction in a deformed (often bent) crystal is described by the Takagi equations 1 which, in general, have to be solved numerically on a regular 2-D grid of points representing a planar cross section of the crystal in which the diffraction of an incident X-ray wavefront occurs . Presently, the majority of numerical approaches are based on a finite difference solving scheme2-4 which can be easily implemented on a regular Cartesian grid but is not suitable for deformed meshes. In this case, the inner deformed crystal structure can be taken into account, but not the shape of the crystal surface if this differs substantially from a planar profile 5,6. Conversely, a finite element method (FEM) can be easily applied to a deformed mesh and serves very well to the purpose of modelling any incident wave on an arbitrarily shaped entrance surface 7 e.g. that of a bent crystal or a crystal submitted to a strong heat load 8-10 …
International Society for Optics and Photonics
Publication date: 
15 May 2017

Ari-Pekka Honkanen, Claudio Ferrero, Jean-Pierre Guigay, Vito Mocella

Biblio References: 
Volume: 10236 Pages: 1023605
Damage to VUV, EUV, and X-ray Optics VI