Development and production of open-type quadrupole magnets with advanced techniques for a 2.5 GeV SRS at CAT

The quadrupole magnets for 2.5 GeV SRS, Indus-2, are characterized by high gradient and stringent magnetic field quality. This requires precise control on magnet geometry during its manufacturing. One type of quadrupole family needs to be an open type to take out SR beam lines. This feature introduces further complexity in the engineering design of the magnets. The magnet cores are made from 1.5 mm thick decarburized steel sheets and their excitation coils are made from hollow OF copper conductors. The core is an assembly of four pole pieces, which are made by laser-cut laminations and consolidated by welding. The pole tip profile was finish machined by wire-EDM. The excitation coils are made using a semi-automatic coil-winding machine. The wound coils are consolidated with vacuum pressure impregnation (VPI) followed by epoxy encapsulation for ground insulation. A number of open type quadrupole magnets have been made successfully and the magnetic characterization has been done. The measurement results meet the stringent beam dynamics specifications. The advanced manufacturing techniques followed for these magnets, their geometrical accuracies and test results are discussed in this paper.