British company Rockwood Composites announced on June 8 that it has successfully assembled core components for the UK's private fusion energy company Tokamak Energy's latest nuclear reactor ST40.
The core component consists of 24 internal units of the toroidal field coil, each unit insulated by a "glass fiber prepreg/Kapton polyimide film/glass fiber prepreg" layer structure. Silicon enhanced curing systems are used to control the position and pressure of the curing process. This allows the air and resin to be gradually extruded from beneath the Kapton polyimide film layer, thereby ensuring that Kapton can be tightly bonded to form a uniform continuous insulating layer on the toroidal field coil.
The thickness of the bond line needs to be precisely controlled. A layer of dry fiberglass fabric was used to control the bond line thickness and the dispersed bond system with a bond thickness of 0.1 mm.
Rockwood applied this insulation to both solenoid coils in the ST40's magnetic fields. Also, a glass fiber prepreg and a Kapton polyimide film are applied between the coils in a spirally overlapping manner during coil winding. Finally, the entire solenoid is wrapped by a fiberglass prepreg.
Rockwood also supplies a low temperature suspension system for the ST40 reactor, which consists of a large number of custom carbon fiber ribbons. The technology is also used in the world's largest and most influential International Thermonuclear Experimental Reactor (ITER) program, which involves engineers and scientists from 35 countries.
Mark Crouchen, head of operations at Rockwood, said: "The nuclear fusion device creates an extreme temperature environment that is harsher than any area in the solar system. The performance of the composite can help the device achieve extreme high temperatures above the sun's core temperature."
ST40 project manager Graham Dunbar added: "We encountered real difficulties in the manufacturing of strong magnetic core components, and Rockwood's team of engineers used composite materials to help us find the best solution."
The successful design of the ST40 demonstrates that it can achieve a fusion temperature of 100 million degrees Celsius in a compact, cost-effective device.
