Kyoto Fusioneering opens dedicated gyrotron facility to close fusion’s heating gap

Kyoto Fusioneering’s gyrotron system delivers 100-170 GHz mm-wave power for electron cyclotron heating, integrating tube, supply and controls at the Shiga factory to enable commercial fusion scaleup.

(Image courtesy of Kyoto Fusioneering)

Gyrotrons are not a glamorous problem in fusion, but they are a real one. Every magnetic confinement program that reaches serious plasma heating ambitions eventually confronts the same constraint: sourcing and integrating high-performance millimetre-wave heating systems from a supply chain built for national laboratories, not commercial schedules. Kyoto Fusioneering’s new KF Shiga Innovation Factory, a 1,770 square metre dedicated R&D facility opening in Shiga Prefecture this autumn, is a direct attempt to fix that structurally.

The physics is straightforward enough. Achieving fusion plasma temperatures requires auxiliary heating, and electron cyclotron resonance heating, where gyrotron-generated millimetre-wave radiation in the 100 to 170 GHz band is directed into the plasma vessel and absorbed by the electron population, is the dominant method across virtually every major program. Japan’s QST demonstrated the manufacturing capability with the eight ITER units it completed in 2021. What has not existed is a private-sector product line capable of repeatable delivery, international qualification, and continuous improvement on commercial timelines.

KF’s gyrotron systems have already shipped to programs in the United States, United Kingdom, Germany, and the Czech Republic. Until now development has been distributed across national laboratory sites, a legacy of publicly funded fusion research that is poorly suited to customers setting hardware schedules in months rather than decades. The Shiga facility consolidates that work onto a single site and, critically, builds fully integrated test infrastructure covering the tube, power supply, cooling circuit, and control system together. System-level testing is what surfaces the real engineering problems, the interactions between a gyrotron tube and a finite-impedance power supply, or a control system required to respond to plasma disruptions in milliseconds, that matter for deployment.

The facility is housed within the Adogawa plant of Nichicon, a company that has been supplying high-voltage pulse power systems to Japanese fusion programs including JT-60SA and the Large Helical Device for roughly 70 years, and which is also an investor in KF. That relationship is not incidental. Gyrotron operation is among the more electrically intensive activities in any fusion facility, and building serious power infrastructure inside an organisation that already understands the requirements shortens the development path considerably.

The broader supply challenge is worth stating plainly. As private fusion programs move from single-device experiments to parallel hardware timelines, demand for gyrotron systems in quantities the existing supplier base has never been structured to meet is coming. Japan’s institutional depth in gyrotron physics, accumulated through ITER and domestic programs, is the asset KF is commercialising. Shiga is the infrastructure that makes that credible at scale.

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