US-based General Atomics (GA) has been awarded a contract by US ITER, based at Oak Ridge National Laboratory, to develop the manufacturing process for components for the system that will transmit microwave heating into the heart of the ITER international fusion reactor under construction at Cadarache in France.
These components, known as waveguide assemblies, are composed of precision-machined, ultra-straight metal tubes up to three metres in length. The assemblies will carry high-frequency, high-power microwaves as part of ITER’s electron-cyclotron heating (ECH) system, which is used to heat the plasma to fusion conditions.
The contract covers development of manufacturing procedures that will be qualified by fabrication of ten ECH transmission line waveguide assemblies at GA’s Magnet Technologies Centre (MTC) in San Diego. Production of the around 1700 waveguide assemblies that will be installed in ITER will be the subject of future US ITER contracts not yet awarded.
GA has been developing and delivering waveguides and related systems in support of fusion and other projects for more than 30 years and its corrugated waveguide technology is being used in fusion experiments around the world. This approach allows for extremely efficient microwave transmission with very little loss of energy over long distances, which is essential for operation of an experiment the size of ITER, GA said.
“The ECH system is a critical component for ensuring ITER’s successful operation,” said Jim Anderson, head of GA’s Radio Frequency Technology department. GA contributes to the ITER project in multiple ways, starting with research at the DIII-D National Fusion Facility, which GA operates as a national user facility for the US Department of Energy’s Office of Science. DIII-D is the largest operating magnetic fusion research facility in the USA.
The MTC, where the waveguide assemblies will be produced, is also the facility where GA is fabricating the ITER Central Solenoid. Standing 59-feet tall, the Central Solenoid will be the largest pulsed superconducting magnet ever built. It will operate at temperatures of 4K and drive 15 million amperes of current into the ITER tokamak to heat and stabilise the plasma. GA is also building several ITER technical systems, including diagnostic devices, and undertaking important theoretical physics research to support the project.
Photo: A rendering of one of the electron cyclotron heating (ECH) waveguide assemblies that GA is developing for the ITER fusion experiment (Credit: General Atomics)