STRAND PRODUCTION AND BENCHMARK TESTING FOR THE ITER MODEL COILS

As part of the technology demonstration for the main features of the I TER Tokamak superconducting coils, two model roils, characteristic bor e 2 divided by 3m, will be manufactured jointly by the four ITER partn ers (EC, JA, RF, US), The coils will require a total of 26 tonnes of N b3Sn strand, supplied equally by each of the partners. The procurement of the strand is proceeding in stages, with performance and continuou s quality demonstrated first on about It from each party underway sinc e Sept, 93 and due for completion by Oct, 94. The strand uses both the bronze and internal tin routes, achieving jc(non copper) in the range 550-700 A/mm(2) 12T and 4.2K, with hysteresis losses from 200 to 600 mJ/cc(nonCu) for +/- 3T cycle. Unit lengths >1.5km are required with d iameters about 0.8mm. The status and parameters achieved in the produc tion is reported. One of the first steps in confirming the strand qual ity has been to establish consistent testing procedures through a benc hmark activity using strand exchange between all parties. The first bl ock of testing was completed in May 94 and a second round is now under way. The results of the two rounds and the steps taken to standardise the testing are described.