Bending magnet

In a bending magnet comprising a core (1) which is substantially sectoral or semi-circular in horizontally sectional configuration and in which opposed magnetic poles (3a, 3b) are formed and a vacuum chamber (4) for storage of a charged particle beam (5) is disposed in a gap between the opposed magnetic poles, and a pair of upper and lower exciting coils (2a, 2a min ; 2b, 2b min ) for generating a bending magnetic field in the gap between the magnetic poles of core, the reluctance against the magnetic flux passing through a portion (7a) of the core adjacent to the inner circumference of the orbit of the charged particle beam and a portion (7b) of the core adjacent to the outer circumference of the charged particle beam orbit is equally uniformed over the overall length of the orbit of the charged particle beam. With this construction, the magnetic flux density becomes uniform in the gap between magnetic poles where the magnetic flux passing through the inner and outer circumference side portions is concentrated and the magnetic flux distribution is uniformed in the orbital direction in the gap, thereby eliminating adverse influence upon the charged particle beam, and the bending magnet can be very effective for use in a synchrotron or a storage ring.