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TY - CONF AU - Sharma, G. AU - Mishra, G. AU - Tripathi, S. ED - Petit-Jean-Genaz, Christine ED - Arduini, Gianluigi ED - Michel, Peter ED - Schaa, Volker RW TI - Design and Magnetic Measurements on Bi-harmonic Undulators J2 - Proc. of IPAC2014, Dresden, Germany, June 15-20, 2014 C1 - Dresden, Germany T2 - International Particle Accelerator Conference T3 - 5 LA - english AB - In recent years there exists interests in harmonic lasing of free electron lasers for short wavelength operation with low energy electron beams. In a planar undulator , the electron radiates at odd harmonics on axis however the harmonic gain of the FEL is much less than that of fundamental. It has been shown in earlier works that it is possible to enhance the harmonic radiation by increasing the harmonic wiggler field to the fundamental by putting high permeability shims inside the undulator. The common material is the vanadium permendur (μ ~800) , which has been used effectively to design the harmonic undulator. In this paper, we report the design and fabrication of seventh and ninth harmonic undulator for free electron laser applications. We use CRGO shims with μ ~ 2-3. The permanent magnet undulator is a four block per period design. The undulator is a variable gap type and consists of NdFeB magnets with six periods, each period is of 5cm length. The undulator has been measured in hall probe and pulsed wire bench. It is shown that the pulsed wire magnetic measurements yields results in close agreement with hall probe results. PB - JACoW CP - Geneva, Switzerland SP - 2013 EP - 2015 KW - undulator KW - laser KW - free-electron-laser KW - electron KW - synchrotron DA - 2014/07 PY - 2014 SN - 978-3-95450-132-8 DO - 10.18429/JACoW-IPAC2014-WEPRO033 UR - http://jacow.org/ipac2014/papers/wepro033.pdf ER -