Teams onsite at the International Thermonuclear Experimental Reactor (ITER) under construction in France have completed installation of the first gyrotron and commissioning tests will start later in September. The microwave-generating device, supplied by Japan, is the first of 24 gyrotrons to be installed on the top floor of the Radiofrequency Building and one of 72 gyrotrons overall that will be needed when scientists introduce tritium for the first time into the ITER device (a scientific phase called DT-1).
Gyrotrons are referred to as “plasma starters” for their role in initiating plasma pulses or “wave generators” for their efficiency at generating high-frequency waves to match the resonant frequency of electrons in the plasma (170 GHz). They are a critical part of auxiliary heating at ITER. Electron cyclotron resonance heating (ECRH) heats the electrons in the plasma; the electrons in turn transfer the absorbed energy to the ions by collision.
The original baseline plan for ITER called for 24 gyrotron devices (eight from Japan, eight from Russia, six from Europe and two from India). The first 16 from Japan and Russia have passed all factory acceptance testing and have been delivered to ITER. One by one, teams will install them in the Radiofrequency Building’s “gyrotron floor” (level 3).
The new baseline, which demands more powerful radiowave plasma heating, has modified plans both for gyrotron procurement and for the Radiofrequency Building. Now 48 gyrotrons will be required at the start of ITER operation and another 24 for the first phase of deuterium-tritium plasma operation (DT-1). This requires additional procurement, an annex to the Radiofrequency Building, and an entirely separate building for equipment for the ion cyclotron resonance heating system.
In a milestone for the radiofrequency heating programme, the installation of the first gyrotron procured by the Japanese Domestic Agency is now complete. It has been connected to its power supply ready for commissioning, one of the highlights of which will be the generation of the first radiofrequency waves.
Meanwhile, in August, scientists and engineers at General Atomics (GA) in San Diego completed the Central Solenoid Modules for ITER that make up the largest and most powerful pulsed superconducting magnet ever built. At nearly 60 feet tall, the Central Solenoid will power fusion reactions at ITER.
“This project signified a watershed moment for the US and for General Atomics,” said Dr Wayne Solomon, Vice President of Magnetic Fusion Energy for the General Atomics Energy Group. “As the first private company to take on the challenge of building fusion magnets at this scale, GA is proud to be leading the way in developing the technologies needed to make fusion power a reality.”
The Central Solenoid consists of six individual sections, or modules, each weighing more than 270,000 pounds. Each module required over two years to fabricate, followed by testing. They will be shipped to France, where they will be stacked to form a colossal system more than 18 metres tall, 4.25 metres) wide, and weighing more than 1,000 tonnes.
The 15-year project was completed inside GA’s Magnet Technologies Center in Poway, California. The large scope of work demanded unprecedented engineering innovation including the creation of novel tools installed in a purpose-built facility that required the support of a specialised global supply chain. The programme has enabled GA to establish unmatched technical capabilities that will serve as a foundation for future fusion technologies. These include blanket component testing and manufacturing large high-temperature superconducting magnets for fusion energy as well as broader non-fusion applications.
General Atomics has long been at the forefront of fusion technology research. From its San Diego headquarters. GA operates the DIII-D National Fusion Facility on behalf of the US Department of Energy, currently the only operating fusion reactor (tokamak) user facility in the US. GA also fabricates the target assemblies that have enabled the National Ignition Facility at Lawrence Livermore National Laboratory to achieve fusion ignition for the first time in history.
In March, US ITER, the United States Domestic Agency for ITER, completed delivery to the site of all components for the support structure for the central solenoid. The support structure was manufactured by eight US suppliers across six states and comprises more than 9,000 individual parts. Its final delivery crossing the Atlantic in January was the culmination of more than a decade of work by US ITER staff and US suppliers.
ITER is a first-of-a-kind global collaboration with construction funded mainly by the European Union (45.6%) with the remainder shared equally by China, India, Japan, Korea, Russia and the USA (9.1% each). However, in practice, the members deliver little monetary contribution to the project, instead providing ‘in-kind’ contributions of components, systems or buildings. The goal of ITER is to operate at 500 MW (for at least 400 seconds continuously) with 50 MW of plasma heating power input. It is not intended to generate electricity. Construction began in 2010 with 2018 targeted for first However, in 2016, the target date was moved to 2025 by the ITER council and has since been advanced to 2035.
