Design and Magnetic Measurements on Bi-harmonic Undulators

In this paper, we report the design and fabrication of seventh and ninth harmonic undulator for free electron laser applications. The permanent magnet undulator is a four block per period design and has been modified with CRGO shims along the length of the undulator. The undulator is a variable gap type and consists of NdFeB magnets with six periods; each period is of 5cm length. The modified bi-undulator has been measured in hall probe and pulsed wire bench