Insulation Materials and Processes for Helium Penetrations

The United States contributions to ITER include the design, development, and construction of the Central Solenoid magnet system. A key challenge in the fabrication of this device is providing electrically insulating the penetrations through which helium enters the magnet system. The proposed program seeks to demonstrate materials and processes to insulation these portions of the device. The proposed work involves the development and testing of insulation materials that can be applied to the helium penetrations within the ITER Central Solenoid. The helium penetrations have tapered shapes, so the insulation must be conformable to the part and readily integrated into the turn-to-turn insulation used on the conductor conduits. In Phase I, CTD demonstrate methods for fabricating net-shape composite insulators, as well as prepreg materials that can be used to electrically isolate the helium supply lines. The materials and components produced in Phase I were shown to provide the necessary electrical and mechanical performance for use in ITER magnet systems. In Phase II, CTD will continue to develop the materials and processes needed to insulate the helium penetrations in the ITER magnet systems. The Phase II efforts will include optimizing the materials and processes developed in Phase I, fabricating assemblies to demonstrate the application of these devices to the ITER Central Solenoid, and adapting these methods for insulating the Helium penetrations in the ITER Toroidal Field (TF) and Poloidal Field (PF) coils. Commercial Applications and Other Benefits: Penetrations and electrical terminations present several challenges to magnet designers because of their complex shapes and the need to join electrical insulations in a manner that will not limit the reliability of the system. In addition to providing materials and processes for ITER, it is anticipated that the products of this work will also be useful in medical devices, accelerator magnets, and superconducting power systems.