摘要
A model helical undulator 250 mm in length, designed and fabricated with a period of 14 mm, was tested in a liquid helium bath. The helical coil was wound with a multifilamentary, tube-type Nb3Sn strand with 217 sub-elements. The coil I-c and the magnetic field in the bore were measured at 4.2 K in a liquid helium bath using a Hall probe. I-c was found to be 842 A, and the bore field reached the design specification of 0.8 T. The transverse bore field was also measured as a function of position along the length of the undulator axis and was seen to exhibit the expected sinusoidal behavior. The measured I-c was compared with that obtained from a crossing of a load line (determined from FEM modeling) with the I-c(B)curve of a short sample Nb3Sn strand. The coil exhibited the same critical current as the short sample.
- 出版日期2012-11