Progress of the ITER central solenoid model coil programme

Abstract

The world's largest pulsed superconducting coil was successfully tested by charging up to 13 T and 46 kA with a stored energy of 640 MJ. The ITER central solenoid (CS) model coil and CS insert coil were developed and fabricated through an international collaboration, and their cooldown and charging tests were successfully carried out by international test and operation teams. In pulsed charging tests, where the original goal was 0.4 T/s up to 13 T, the CS model coil and the CS insert coil achieved ramp rates to 13 T of 0.6 T/s and 1.2 T/s, respectively. In addition, the CS insert coil was charged and discharged 10 003 times in the 13 T background field of the CS model coil and no degradation of the operational temperature margin directly coming from this cyclic operation was observed. These test results fulfilled all the goals of CS model coil development by confirming the validity of the engineering design and demonstrating that the ITER coils can now be constructed with confidence.

Review of Nb3Sn conductors for ITER

“…a layer or a pancake)) [1,3]. Therefore, the assessment had to rely on thermohydraulic and electric models.…”

“…However, note that these coils were not initially intended to be used for conductor T cs measurement. The CSI results, thanks to a simpler structure and a better instrumentation, were easier to analyze [1]. The TFI results were not so easy to assess due to discrepancy among temperature sensors and to possible effects of one damaged/repaired joint [2].…”

“…The ITER model coil program consisted of the CSMC and two associated insert coils, the central solenoid insert (CSI), the toroidal field insert (TFI), and the TFMC, which all use Nb 3 Sn conductors [1][2][3]. A third CSMC insert coil, the aluminium insert (ALI) which used Nb 3 A1 conductor will not be considered here.…”

“…Before 2001, this tension was considered as fully transmitted to the Nb 3 Sn filaments and so added to ε th as an operating strain ε op to get the effective strain ε eff according to (1). Values are given in Table 1 (CS conductor jacket is in Incoloy):…”

Overview of the hydraulic characteristics of the ITER Central Solenoid Model Coil conductors after 15 years of test campaigns

“…Moreover, the hydraulic characteristic of the conductors plays a significant role during off-normal transients, such as a quench event, in determining the quench propagation speed along the conductor. For the ITER magnet system, the fully superconducting Central Solenoid Model Coil (CSMC) [3], see figure 1a, a solenoid in operation since 2000 at the National Institutes for Quantum and Radiological Science and Technology (former JAEA) plays a relevant role in the related R&D as it is the only facility worldwide allowing the test of full-length ITER conductors in a background field up to 13 T. Since its commissioning, more than 15 years ago, the CSMC has operated several times during the test campaigns of the ITER Insert Coils, tested in the bore of the CSMC in 2000,2001,2002,2004,2015 and 2016-17, respectively.…”