Six ring-shaped poloidal field coils are situated outside of the toroidal field magnet structure to shape the plasma and contribute to its stability by "pinching" it away from the walls. The largest coil (PF3) has a diameter of 24 meters; the heaviest (PF6) is 400 tones. The PF coils are all wound with NbTi conductors with a two-in-hand configuration which are designed to produce a total magnetic energy of 4 gigajoules and a maximum magnetic field of 6 tesla.
The PF6 coil has an outer diameter of ~10.2m, inner diameter of ~7.1m, height of ~1.3m, which is composed by 9 double pancakes stacks and bonded together with ground insulation by VPI.
The PF magnet system
Overview of PF6 Coil
An agreement on PF6 coil manufacturing between F4E (Fusion for Energy) and ASIPP (Institute of Plasma Physics Chinese Academy of Sciences) was signed in October 2013 and the coil was expected to delivered around the end of 2018. The PF6 coil is the only PA that EU outsourced overseas ，and a dedicated workshop with environment and cleanness control was built at a waterborne site in Hefei,China.
A team of about 70 staff were employed for the project, most of whom have acquired valuable experiences from EAST and ITER CC project. The bulk-production work of 9 double pancakes for PF6 near the end and the project now entering a new phase called Coil production(assembly manufacturing).
At the end of 2016, the PF6 program successfully completed the qualification of all key components.Up to 100 pre-research experiments have been carried out in the early stage of PF6 project. The manufacturing level of winding, joint, insulation and other processes has been quite mature, and most of the technical processes for PF6 project have been reached the world advanced level.
In January ,2017, the winding work for the first PF6 full-size double pancake had been completed. This is the first time that a large size component with high precise winding technique has been verified.
The VPI insulation treatment of Dummy double pancakes of PF6 coil was successfully completed and the test results met the predetermined technical requirements in July,2017. which comprehensively and systematically verified the stability and reliability of the insulation system and VPI process.
In March ,2017, PF6 coil formally entered the stage of mass production. Up to now, eight double pancakes’ manufacturing work has been compeleted so did the winding work. The mass production work for 9 pancakes is about coming to an end. It is estimated that all work for pancakes will be completed in September,2018 and the PF6 coil will be formally delivered to ITER in April,2019.
PF6 manufacturing building