Design and Fabrication of a Special Purpose Winding Machine for ELM Control Coils of JET

Under the India-European Union collaboration, the Institute for Plasma Research had successfully completed an engineering initiative aimed at developing a “special purpose winding machine” (SPWM) appropriate for winding 1:1 prototype edge-localized mode (ELM) coils of the Joint European Torus (JET). The typical 1:1 prototype ELM coil winding pack is composed of eight layers of 6.35-mm square cross-section CuCrZr conductors being wound in a saddle configuration having eight turns per layer with strict tolerance requirements. Such an SPWM has been designed and developed with Indian industry complying with the complex shape and tolerance requirements of the ELM coils. The SPWM developed is primarily composed of a feeding conductor spool with appropriate tensioning mechanisms, straightening and shaping units, cleaning unit, insulation unit, press forming units and rotating turn table mandrel, and rotation and synchronization arrangements with electrical control and feedback elements. The SWPM has been successfully demonstrated with winding for both types of 1:1 prototype ELM control coils of JET within a tolerance of ±3 mm. The design consideration for SPWM, critical subsystems of SPWM and their operation principle, winding methodology, and application articulated arm coordinate measuring machine for inspection of winding pack have been discussed in this paper.