Magnetic Measurement of the Current Center Line of the Toroidal Field Coil of ITER at Room Temperature

Self Cite

The ITER Magnet System contains 18 Toroidal Field Coils (TFC). These are large D-shaped coils of about 300 t, 17.5-m height and 9-m width. They consist of a Winding Pack (WP) enclosed in a rigid structural steel case, the Toroidal Field Coil Case (TFCC). The WP is a bonded structure of 7 Double Pancakes (DP), each made up of a radial plate (RP) housing the reacted cable-in-conduit superconductor (CICC), which operate at 4.5 K in supercritical helium. The conductor carries a current of 68 kA in operation to produce a nominal peak field of 11.8 T. The total stored magnetic energy in the 18 TFCs is 41 GJ. While the Japanese and European Domestic Agencies that are in charge of the procurement of the TFCs are progressing with the manufacturing design and the fabrication trials prior to launch the production of the real coils, the ITER Organization (IO) is completing the development and qualification of the most critical items, e.g. cyanate ester and resin blends for the conductor and WP insulation system, the terminal region, the helium inlet, a charged resin system for the filling of the gap between the WP and the TFCC and the general tolerancing especially at the interfaces between the neighboring systems. This paper presents the final design of the TFCs and the results of the developments carried out in the aforementioned areas in the last 2 years.

Section: Tolerances and CCLmentioning

confidence: 99%

The Toroidal Field Coils for the ITER Project

Savary

Gallix

Knaster

et al. 2012

Self Cite

“…For ITER magnets [2], the reference CCL of the toroidal field (TF) coils is defined [3]. Several contributions modeling such a measurement [4], [5], [6], [7], describing the validation of the measurement procedures [8], [9] as well as discussing manufacturing [10], [11] and assembly [12], [13] issues are available.…”

mentioning

confidence: 99%

Magnetic Determination of the Current Center Line for the Superconducting ITER TF Coils

Lerch

Buhagiar

Wassmer

et al. 2015

The ITER tokamak includes 18 superconducting D-shaped toroidal field (TF) coils. Unavoidable shape deformations as well as assembly errors will lead to error fields in the final configuration, which can be modeled with the knowledge of the current center line (CCL). We are building a room temperature magnetic measurement system using low frequency ac excitation current through the TF coil and arrays of pick-up coils, fabricated with printed circuit board technology. Deviations from the expected shape of the CCL will be obtained by comparing the amplitude of magnetic flux measured at several locations around the perimeter of the TF coil, with values computed assuming the nominal current distribution. We present experimental results obtained with a cable placed in one turn groove of a full scale radial plate.

Magnetic Measurements for Magnets Manufacturing Tolerances Assessment

Bellesia

Oliva

Boter

et al. 2014

Superconducting high field magnets are tightly constrained in terms of field quality, since such magnets are usually designed to perform quite demanding tasks, such as focusing particle beams in accelerators, plasma confinement and shaping in fusion devices, and polarizing actions in magnetic resonance. In all these cases, small discrepancies of field map from the design values may strongly impact on device performance. As a consequence, quality insurance procedures are needed to verify if each single coil meets such criteria, e.g., using laser tracking, and possibly warm magnetic measurements. As a matter of fact, external magnetic measurements can be used to estimate the possible deformations of conductors inside the magnet, but this implies inverse problem approaches. The field probes accuracy is therefore critical, and the measurement system must be carefully designed, taking into account the probe characteristics, but also the characteristics of the windings and of the surrounding environment. In this paper, different measurement techniques are compared in terms of sensitivity and accuracy, with reference to various types of sensors and of measurement schemes.