Operation of a 20-T superconducting magnet with a large bore

In March 1993, the highest magnetic field of 21.1 T was generated in a 50 mm diameter clear bore. It was accomplished by using a 20 T superconducting magnet with a large bore developed at the National Research Institute for Metals. In order to obtain higher fields over larger spaces, three Wind and React coils having identical winding parameters were fabricated as the innermost coils. By removing a stainless steel bobbin from the second coil, improvement of training behavior as well as enlargement of a clear bore diameter could be achieved. A bobbin was also removed from the third coil. It was wound with a newly developed conductor and recorded the field of 21.1 T