Long Rotating Coil System Based on Stretched Tungsten Wires for Insertion Device Characterization

A very precise rotating coil was developed using stretched tungsten wires in a new geometric arrangement for the accurate magnetic characterization of insertion devices (IDs). Many sources of errors were analyzed, and a procedure to evaluate coil defects by means of a dipolar magnetic field is presented. Tests were performed in a 2-T planar wiggler, which is 2.8 m long, with 180 mm of period, of the Brazilian synchrotron light source (LNLS). The advantages of using the tungsten wires and the measurement repeatability and accuracy are also discussed.