A Method for Measurement of Transverse Impedance Distribution along Storage Ring

A new method for measurement of transverse couple impedance distribution along storage ring is described. The method is based on measuring of a closed orbit deviation caused by local impedance. Transverse impedance acts on the beam as a defocusing quadrupole, strength of which depends on the beam current. If a local bump of closed orbit has been created at the impedance location, then the orbit deviation occurs while varying the beam current. The local impedance can be evaluated using the orbit deviation measured. Measurement technique is described, the method accuracy is evaluated. The method described was successfully used for measurement of the impedance distribution along the VEPP-4M storage ring.