Magnetic field measurement on superconducting multipole wiggler with narrow duct

The first superconducting multipole wiggler with period length of 6.0 cm (SMPW6) of the National Synchrotron Radiation Research Center (NSRRC) is currently under construction. SMPW6 will be tested and installed at the RF cavity section of storage ring by the autumn of 2003. For quality control, the magnetic field is checked at three main phases according to the assembly process. To operate the field measurement in a narrow duct and at different temperature of duct at different phases, three small-gap measurement systems were specially designed. Not only the centerline field can be measured point-by-point but also the multi-pole field can be mapped. All the measurement systems have been carefully tested. The consideration of the measurement systems and preliminary measurement are shown in this paper.