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Description
Fusion plasma confinement at facilities based on a tokamak geometry of the magnetic field includes periodical transient heat loads to divertor plates. The divertor plates of ITER are seem to be covered by polycrystalline tungsten. The tungsten tends to crack in case of the pulsed heating. The reasons of the crack formation are deformations and mechanical stresses caused by the sharp rise in temperature of thin surface layer. The X-ray scattering station «Plasma» at the beamline 8 at the VEPP-4M source of synchrotron radiation was developed for dynamical measurements of deformations and mechanical stresses in tungsten during pulsed heating simulating by laser radiation. First results were carried out on the mosaic single-crystal tungsten. The observed evolution of the diffraction peak shape agrees with theoretical predictions based on calculations of deformation caused by pulsed heating. Deconvolution of the residual stress distribution show good agreement with theoretical model of distribution of the deformations in thin surface layer in the sample during pulsed heating. One of the most important cases was the observation of the bifurcation of the diffraction peak during the occurrence of the crack on the sample during sequential repeated irradiations of the sample. Moreover, the first experiments on the measurements of the diffraction on polycrystalline tungsten were carried out.
