Diffraction of x rays in capillary optics

Propagation of x rays generated by a small-diameter incoherent source through the capillary waveguide that satisfies the multimode condition is studied with the Fresnel - Kirchhoff diffraction theory. The strong influence of diffraction on the propagation is demonstrated. The diffraction phenomenon is manifested by the appearance of diffraction fringes in both the guide channel and the far-field zone of the capillary output. Experimental data that confirm such behavior of the x-ray radiation is also presented. The results confirm the interference effects recently observed in some experiments on the grazing reflections of x rays in single-and multiple-capillary optics.