Superconducting Nb3Sn solenoids operating at 15 - 16.5 T

Present state of the art in tape wound Nb3Sn solenoids is the generation of magnetic fields above 15T in clear bore diameters up to 65 mm. Details of the construction and operation of magnets of this type, especially the first one which achieved 15.8T in a 26 mm bore at 4.2K are given. The operation of this solenoid at reduced temperatures in a pumped helium bath is described. The solenoid was operated at various temperatures to below 3K where a maximum field of 16.5T was observed, limited only by mechanical strength. The prospect of achieving even higher fields at 4.2K and lower temperatures is discussed in terms of the properties of Nb3Sn and practical design considerations.