On July 25 , 2001 the Nb3Sn superconducting ITER Toroidal Field Model Coil (TFMC) , installed in the TOSKA facility at the Forschungszentrum Karlsruhe, reached the maximum current of 80 kA allowed by the facility, corresponding to a maximum magnetic field of nearly 8 T.
ITER is an International collaboration between the European Union, Japan and the Russian Federation, under the auspices of the International Atomic Energy Agency, to build an experimental reactor for the demonstration of the scientific and technological feasibility of fusion as one energy option for the future.
The construction and test of the Toroidal Field Model Coil is one of the seven Large R&D Projects within the ITER activities.
After having achieved, on the 19th July, an operating current of 57 kA, the power supply control system had to be readjusted. On the 23rd July the test program was resumed and 69.3 kA were reached on the 24th July. This value is already above the nominal current of the toroidal field coils which are planned for the ITER machine.
On the 25th July the TFMC was ramped up to the maximum current of 80 kA allowed by the facility, corresponding to a maximum magnetic field of nearly 8 T.
The behavior of the superconductor and of the joint resistances are as expected, as well as the temperature increase in the structures during fast ramp down and safety discharge.
The NbTi busbars carried 80 kA at a maximum magnetic field of about 3 T and at a cryogenic temperature of about 5 K. At that field level the joints behaved better than expected. These results are a preliminary confirmation that the design of the ITER Poloidal Field coils is viable.
The test program will continue to explore the operational limits of the coil and validate the design codes. Both are needed to optimize the ITER operating parameters’ space and cost.
The TFMC has been conceptually designed by the European research laboratories working on fusion. A consortium of European companies, called AGAN, have performed the engineering design of the coil and manufactured the TFMC under the management of EFDA/CSU Garching. The TFMC was then shipped to the TOSKA facility at the Forschungszentrum Karlsruhe where it is being tested.
The objectives of the TFMC project are to demonstrate the manufacturing feasibility of very large Nb3Sn coils, as needed for ITER, the ability to reach the required industrial tolerances and to explore the coil operational limits.
It is foreseen that the testing of the coil will extend into next year.