Superconducting Coil Manufacturing Method for Low Current DC Beam Line Magnets

A method of manufacturing superconducting multipole coils for 40 to 50 kG DC beam line magnets with low current is described. We built small coils and tested them successfully to short sample characteristics. The coils did not train after the first cooldown. The coils are porous and well cooled to cope with mechanical instability and energy deposited in the coil from the beam particles. The coils are wound with insulated strand cable. The cable is shaped rectangularly for winding simplicity and good tolerances. After the coil is wound, the insulated strands are electrically connected in series. This reduces the operating current and, most important, improves the coil quench propagation due to heat conduction of one strand adjacent to the other. A well distributed quench allows the magnet energy to distribute more uniformly to the copper in the superconductor wire, giving self-protected coils. We are now fabricating a one-meter long, 43 kG. 6-inch bore tube superconducting dipole. The porous coil design and coil winding methods are discussed.