Development of an undulator with a variable magnetic field profile

An undulator generating a magnetic field whose longitudinal profile is arbitrarily varied has been developed, which one of the key components in number proposed new concepts free-electron lasers. The composed magnet modules, each corresponds to single period, and driven by linear actuator change gap independently. To relax requirement on actuator, mechanical load module due force acting from opponent adjacent modules reduced means two kinds spring systems. performance constructed successfully demonstrated measurement characterization synchrotron radiation.