A 50 mm bore superconducting dipole with a unique iron yoke structure

A 50-mm-bore superconducting dipole with a thin stainless steel collar and a close-in elliptical iron yoke was designed to obtain a high transfer function and low saturation effects on the multipoles. A 1-m model was built and tested. The training behavior of the first 1-m model is presented at 4.3 K and 1.8 K. At 1.8 K it reached the record field of 10.06 T. The two layer cos theta winding uses 30 and 36 strand cables identical to the cables of the 50-mm-bore Superconducting Super Collider (SSC) dipole, and it has an operating field of 6.6 T at 4.35 K with a current of 5800 A. To evaluate behavior at high fields, the mechanical structure for the model was designed for 10 T. The thin collar itself provides only a minimum prestress of 10 MPa, and the full prestress of 70 MPa is given by the iron yoke. An aluminum spacer is used to control the gap size in the vertically split iron yoke. The tapered gap in the yoke is determined by the size of the Al spacer so that during cooldown there is no loss of coil prestress and the gap remains closed when the magnet is energized.<>