Helical Fusion selects NIFS campus for Helix HARUKA magnet build, pushing Japan’s stellarator toward hardware reality

Concept rendering of Helical Fusion’s Helix HARUKA integrated demonstration device

(Image courtesy of Helical Fusion)

Japanese stellarator developer Helical Fusion has confirmed the construction site for Phase 1 of Helix HARUKA, its integrated demonstration device. The company now assembles the magnet demonstration phase in a dedicated workspace on the National Institute for Fusion Science campus in central Japan. As a result, Helical Fusion shifts from design into manufacturing and hardware integration. For engineers tracking magnetic confinement approaches beyond the tokamak, this represents a concrete step toward validating a non-planar helical high-temperature superconducting magnet system.

Specifically, Phase 1 centres on assembling and current-testing an HTS magnet in the helical geometry unique to the stellarator concept. Helical Fusion has already entered manufacturing and begun site build-out. The company targets energization tests for 2027. In any magnetic confinement fusion device, magnet performance defines the boundaries of plasma confinement and field strength. It also shapes device reliability and reactor economics. Therefore, validating this hardware early is a prerequisite for everything that follows.

NIFS stellarator heritage powers a new public-private model

The project advances what the company calls a Japan-style public-private partnership for fusion commercialisation. Notably, NIFS brings decades of helical stellarator research and operation of the Large Helical Device. LHD ranks among the world’s largest stellarator-type plasma experiments. Through LHD, NIFS has demonstrated plasma durations of 3,268 seconds. It has also accumulated deep operating know-how in plasma stability control and heat load management. Helical Fusion, founded in 2021 as a NIFS spin-out, contributes private-sector speed and plant-level system integration. In addition, industrial manufacturing partners round out the build-and-test loop.

Helix HARUKA roadmap and HTS magnet milestones ahead

The broader Helix Program roadmap extends through two further stages. In Phase 2, Helical Fusion combines the HTS magnet with blanket and divertor systems. The team then targets sustained high-temperature plasma operation long enough to build engineering confidence toward steady-state power plant design. However, no power generation occurs during Phase 2. The final stage, Helix KANATA, serves as the first power-generating unit. It aims to demonstrate net-electric operation, steady-state performance, and maintainability.

Helical Fusion targets standalone HTS magnet and blanket demonstrations during the 2020s. Consequently, integrated demonstration and commercially viable power generation follow in the 2030s. In December 2025, the company signed Japan’s first fusion power purchase agreement. It also closed a USD 5.5 million Series A extension. The stellarator path has always been the slower bet against tokamak scaling. Still, steady hardware milestones like this one compress the timeline in ways that matter for commercial readiness.

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