517 research outputs found
The experimental study of the surface current excitation under the influence of a relativistic electron electromagnetic field
The problem of the surface current excitation in a conductive targets by a
relativistic electron electric field as the origin of such radiation mechanisms
as diffraction and transition radiation of relativistic electron was considered
in frame of both surface current and pseudo-photon methods. The contradiction
between these viewpoints in respect to the surface current on the target
downstream surface necessitated the experimental test of this phenomenon. The
test performed on electron beam of the 6 MeV microtron showed, that not any
surface current is induced on the target downstream surface under the influence
of a relativistic electron electromagnetic field in contrast to the upstream
surface. This is important implication for the understanding of the forward
transition and diffraction radiation nature.Comment: Was Presented at the symposium Channeling 2008 (Charged and Neutral
Particles Channeling Phenomena), October 25 - November 1, 2008 Erice (Trapani
- Sicily), Italy, and was accepted for publication in proceedings of
symposiu
Experimental Research of the Diffraction and Vavilov-Cherenkov Radiation Generation in a Teflon Target
Geometry of Vavilov-Cherekov (VChR) radiation when an electron moves close to
a dielectric target is in analogy to diffraction radiation (DR) geometry. In
this case we may expect DR generation from the upstream face of the target
besides that VChR. The joint observation of these booth types of radiation is
very interesting from the pseudo-photon viewpoint, which is applicable for
relativistic electrons. Unexpected results obtained in our experiment insist on
reflection about nature both DR and VChR. The experiment was performed on the
relativistic electron beam of the microtron of Tomsk Polytechnic University.Comment: This article will be published in Journal of Physic
Solution of Creep-Damage Problems for Beams and Rectangular Plates Using the Ritz and the Finite Element Method
 
On the accuracy of creep-damage predictions in thinwalled structures using the finite element method
The constitutive model with a single damage parameter describing creep-damage behaviour of metals with respect to the different sensitivity of the damage process due to tension and compression is incorporated into the ANSYS finite element code by modifying the user defined creep material subroutine. The procedure is verified by comparison with solutions for beams and rectangular plates in bending based on the Ritz method. Various numerical tests show the sensitivity of long-term predictions to the mesh sizes and element types available for the creep analysis of thinwalled structures
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