Fusion Energy is one of the most promising energy sources for a sustainable future. With abundant fuel, virtually no CO₂ emissions, intrinsic safety, and unmatched energy density, fusion could provide clean and reliable power for generations to come.
Within this ambitious global effort, the JT-60SA tokamak, a joint project between Europe and Japan, represents a crucial milestone. Among its many challenges lies the need for advanced components that enable plasma heating at extreme temperatures. Here, SAES RIAL Vacuum, in collaboration with Fusion for Energy (F4E), has played a fundamental role.
Fusion energy: the context
Fusion reactions are fueled by isotopes of hydrogen, requiring only a few dozen kilograms of fuel to match the energy output of entire oil tankers. Unlike conventional energy sources, fusion is inherently safe and produces no greenhouse gases during operation.
In today’s geopolitical landscape, the need for energy independence and sustainability has accelerated Europe’s commitment to invest in skills, expertise, and industrial partnerships. Fusion, once a field dominated by publicly funded research, is now also attracting private investment thanks to its enormous strategic and economic potential.
The JT-60SA challenge
Located in Naka, Japan, JT-60SA is the largest superconducting tokamak ever built. It has been designed to support ITER and to pave the way towards DEMO, the demonstration reactor that will prove the viability of fusion energy at industrial scale.
To achieve fusion, plasma must be heated to over 100 million °C. One of the most effective systems for this is Electron Cyclotron Resonance Heating (ECRH), which uses high-power radiofrequency (RF) waves that resonate with the electrons in the plasma. Efficient transmission of this power from the source to the reactor vessel, however, requires highly specialized components.
The diamond window solution for JT-60SA
A central element of the ECRH system is the synthetic diamond window.
Placed within the RF waveguides close to the tokamak vessel, it performs a double function: allowing RF power transmission with minimal losses and separating the machine vacuum from the waveguide vacuum.
The window consists of a synthetic diamond disk housed in a cooled casing that ensures stability, durability, and vacuum tightness. Diamond is the only material capable of transmitting up to 1 MW of power with extremely low absorption, making it an irreplaceable solution for fusion energy applications.
SAES RIAL Vacuum’s contribution
For JT-60SA, SAES RIAL Vacuum was awarded the contract to manufacture a complete set of integrated diamond windows.
This represented a strategic novelty: unlike previous projects, where integration between disk and casing was handled by the client, SAES delivered the fully integrated unit. This innovation marked a step forward towards greater industrial involvement in the fusion supply chain, an essential factor for the future of large-scale reactors.
Our technical proposal, high-quality engineering, and collaborative approach with Fusion for Energy were key to the success of this project. The challenge required expertise not only in advanced materials, but also in vacuum-compatible mechanical systems and innovative custom solutions—areas where SAES RIAL Vacuum has long-standing experience.
“This collaboration added a further step to the development of an industrial ecosystem fit for the development of fusion as reliable and clean energy source.”
Looking ahead
The JT-60SA project confirms how the joint efforts of research organizations and industry are paving the way for fusion as a reliable, safe, and clean energy source.
For SAES High Vacuum, it is a further step in a journey that spans from NEG pumps to customized vacuum solutions, always with the goal of shaping future-proof materials and technologies.
Learn more about SAES High Vacuum’s contribution to Fusion Energy by visiting the following link.