Recent progress of U-shaped rotating anode X-ray source

A U-shaped design for rotating anode X-ray sources is one method for enabling high brilliance, and was first proposed by Professor N. Sakabe (KEK, Tsukuba, Japan) in 1995. Unlike ordinary rotating anode X-ray sources, the electron beam goes beyond the outside surface of the rotating anode and then reverses its direction so that it can hit the inside surface. In this case, because of the centrifugal force of the rotating anode, the surface can be much smoother than usual even near the melting point, enabling the production of more X-ray photons. A KEK research group has published a report on recent progress with this type of X-ray source. According to their simulation, by optimizing both the bending and the steering magnets, the beam size can be 0.45 mm (horizontal) × 0.05 mm (vertical) for a 120 keV/75 mA beam. The effective brilliance is about 500 kW/mm². For more information, see the paper, "Research and development of an electron beam focusing system for a high-brightness X-ray generator", T. Sakai et al., J. Synchrotron Rad. 18, (2011) (Published online, DOI:10.1107/S0909049510029948).