Impedance Studies for Elliptical In-Vacuum Undulator IVUE32

Abstract IVUE32, an elliptical in-vacuum undulator, is being developed at Helmholtz-Zentrum Berlin. The 2.5m long device with a period length of 32mm and a minimum gap of about 7mm is to be installed in the BESSY II storage ring. Allowing not only gap changes but also longitudinal shifts puts novel design challenges on the tapers at the entrance and exit of the undulator. The proximity of this complex structure to the electron beam makes the device susceptible to wakefield effects which can influence beam stability. A complete understanding of these phenomena is required prior to installation and operation. To understand and measure the IVU’s impedance characteristic s a Goubau-line test stand is being designed to accompany simulations. Taper prototypes will be presented alongside simulations and measurements of their impedance characteristics.