Wiggler magnet.

The wiggler consists of magnet system with alternate magnetic polarity and is set in the straight section of a storage ring. It produces synchrotron radiation independently of the normal bending magnets. With the progress of the study on utilization of synchrotron radiation, the wiggler has become an important device as a high intensity light source which attracted attention of researchers. For the past decade, many wigglers have been constructed in several countries. As the operational experience are accumulated, the beam-dynamical problems with the wiggler became gradually clear. In the recent storage rings which are dedicated to the synchrotron radiation use, the main parameters are chosen so as to obtain the optimum spectrum of the wiggler radiation. In this description, at first some results derived from wiggler theory are reviewed briefly, which are useful for the wiggler magnet design, then the characteristics of the periodic magnet-field are described and finally some wigglers (mainly with the superconducting magnets) in operation in the world are surveyed.