Performance of the eight superconducting quadrupole magnets for the TRISTAN low-beta insertions

The low-beta insertion quadrupoles are iron-free superconducting magnets with an inner coil diameter of 140 mm, an effective length of 1.14 m, and a nominal gradient of 70 T/m. The coils, which are of the cos 2 Theta type, are made from four layers of 27-strand NbTi Rutherford-type cable with Kapton insulation and are firmly clamped with 316LN stainless steel collars. Following the development of prototype magnets, eight magnets have been produced and were thoroughly tested and measured prior to installation in the TRISTAN main ring. A brief description of the design and manufacturing technique and the results of tests and measurements are presented.