The ITER Toroidal Field Model Coil (TFMC) was built by European industry according to the conceptual design, which was elaborated by the European Associations under the coordination of EFDA. The objective of the project is to develop and demonstrate the superconducting magnet technology to a level that will allow the ITER toroidal field coils to be built with confidence. The construction and test of the TFMC is one of the seven large ITER R & D projects within the ITER activities.

After the first batch of tests in 2001, the TFMC was tested in the second half of 2002 in the background field of the existing Euratom Large Coil Task (LCT) coil in the TOSKA facility at Forschungszentrum Karlsruhe (Germany). The aim of the TFMC test phases was to verify the design concept and the industrial manufacturing procedures, as well as the achievable tolerances. To validate the design parameters, the mechanical strength of the structures and the current carrying capacity were tested at the rated values of 70 kA, 8.8 T and 4.5 K. Furthermore the operation limits of the “Cable-in-Conduit” conductor were to be checked.

The LCT project was undertaken in the framework of an international collaboration of Euratom, Japan, Switzerland and the US under the auspices of the “International Energy Agency” (IEA). The Euratom LCT coil was first tested in the TOSKA facility in 1984.

The testing of the model coil was organized in two phases. During Phase I, which was carried out in 2001, the TFMC was tested as a single coil:
June, 25: The cool down started. The circuits of the coil were cooled by supercritical Helium, which maintains its cooling power by forced mass flow driven by pumps operating at 4.5 K.
July, 6: The transition to the superconducting state was reached for the first time.
July, 23: At the end of the ITER Engineering Design Activities (EDA), the TFMC operated as a single coil reached its maximum current of 80 kA.

The TFMC was intentionally quenched nine times, before and after being cycled, without counting safety discharges. There were no negative consequences arising from the quenches or from the cycling. For preparing Phase II the ITER TFMC and the Euratom LCT coil were assembled as a single structure and re-installed in the TOSKA vacuum vessel. This was completed in the first half of 2002.
August, 20: the cool down started.
September, 3: the superconducting state in TFMC was reached again
September, 26: the coil testing of phase II started. The TFMC was energized alone up to 80 kA, which repeated the result of last year’s test.

The Euratom LCT coil, providing the background field for the test of TFMC, was also tested alone: first at a winding temperature of 4.5 K to a maximum current of 11.3 kA, and later at a winding temperature of less than 3.1 K to a maximum current of 16 kA. Finally the coil assembly was energized to the rated values of 70 kA in TFMC and 16 kA in LCT. This corresponds to 8.78 T maximum field at the conductor of the TFMC and 282 MJ of stored energy in both coils.

1995: The ITER TFMC project started

1997: Engineering design was completed

2000: The construction of the coil based on new design principles and manufacturing methods was completed
July, 23, 2001: The TFMC reached its maximum current of 80 kA.
Dec. 2002: The Testing of the TFMC in the background field of the existing LCT coil was successfully completed.

In order to check the mechanical rigidity of both winding pack and coil case, the TFMC was cycled in the background field of the Euratom LCT coil, which was kept in steady state operation at 16 kA while the TFMC was ramped up and down to the maximum current in several steps, starting at 17.5 kA and ending at 70 kA. During this second phase the TFMC was intentionally quenched twice.

For the case of maximum currents (80kA in the TFMC and 16 kA in the Euratom LCT coil, 9.67T magnetic field at the conductor of TFMC) the design parameters of the conductor were confirmed. Phase II was successfully completed in December 2002. All tests have achieved the expected results and the operating conditions for ITER have been confirmed with a reasonable temperature margin.

TOSKA vessel:
4.45 m Ø, 6.6 m high

2.73 m wide, 0.77 m thick,
3.8 m high, weight 34 t

Intercoil structure (ICS):
4.03 m wide, 0.70 m thick,
4.67 m high, weight 24 t

LCT coil:
3.5 m wide, 0.82 m thick,
4.6 m high, weight 59 t

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