Improvements in the properties of internal-tin Nb3Sn

A review is given of the present status of Stage IV of the strand production at IGC for the Central Solenoid (CS) Model Coil for the International Thermonuclear Experimental Reactor, (ITER). The design of this production strand was essentially frozen more than a year ago but a parallel development program has been carried out to improve the properties of internal-tin processed Nb,Sn for fusion and other applications, The H-c2* and T-c* have been raised, the J(c) controlled over a wide range of values, and the losses lowered in a number of different ways, An examination of the microstructure and electrical properties after a series of different thermomechanical treatments has been carried out and some of the preliminary results are described.