The process of generation of X-ray radiation formed during the free exit of a fast stream of water in a state of cavitation from a narrow channel was investigated both experimentally and theoretically. It was observed for the first time that the initial part of the stream and the outlet of the channel are the sources of intensive X-ray radiation (with an activity of 0.1 Cu), which is connected with the cavitation phenomena and the following excitation of shock waves. The frequency of the X-ray radiation depends on the composition of the radiating surface (water or the surface of the channel walls) and increases with the increase of the atomic number of the surface. The mechanism of radiation generation is connected with the influence of cavitation shock waves formed on the nearest interface (water-air, water-metal, metal-air, air-metal, etc.).
47.55.dr Interactions with surfaces
61.80.Cb X-ray effects
$^1$Faculty of Physics, Moscow State University, Moscow, 119991, Russia
$^2$Shevchenko National University of Kiev, Kiev, 01033, Ukraine
$^3$Moscow State Technical University (MSTU), Moscow, 105005, Russia