Helical Fusion Takes the Twisted Path

Private

Helical Fusion is a Tokyo startup that wants to build a fusion power plant based on the helical design, a twisted magnetic cage that Japan has studied for decades. Founded in 2021 by a former banker and two researchers from the National Institute for Fusion Science, it has raised about 38 million US dollars, including grants and loans, and tested a large high-temperature superconducting coil in 2025. This profile explains its approach, its milestones and what it offers overseas partners.

Why the helical design

Most fusion projects use a tokamak, a doughnut-shaped device that drives a large electric current through the plasma to help hold it in place. That current makes tokamaks prone to sudden disruptions and makes continuous operation hard.

A helical device, from the same family as the stellarator, shapes the magnetic field with twisted external coils instead. Because it does not rely on a plasma current, it can in principle run continuously. Helical Fusion’s design is a type known as a heliotron.

Japan is one of the world leaders in this approach. The National Institute for Fusion Science (NIFS) in Gifu Prefecture operates the Large Helical Device, one of the largest helical machines ever built, and has run long-duration plasma experiments on it since 1998. Helical Fusion’s founders come from that research community.

The company and its funding

Helical Fusion was founded in 2021 by Takaya Taguchi, a former banker who serves as CEO, together with two NIFS scientists. Its funding combines private capital with public support.

The 2025 coil test

The hardest engineering problem in a helical reactor is the magnet system. The coils are large, twisted and must stay superconducting for years. In October 2025 Helical Fusion reported that a large conductor made with high-temperature superconducting (HTS) tape carried a stable current of 40 kA in a 7-tesla external field at 15 K (about -258°C). The test was carried out at a NIFS high-field facility.

The company describes this as the first successful test of a large-scale, uninsulated HTS conductor of its kind. HTS magnets can produce stronger fields in smaller devices, which is a key reason many fusion startups have moved to them.

The roadmap

• Helix HARUKA — An integrated demonstration device now being built to test the magnets, blanket and divertor together. Blanket and divertor tests are planned by the end of the decade.
• Helix KANATA — A full-scale pilot plant aimed at steady-state, net-electric fusion power in the 2030s.

These dates are the company’s own targets. Like every fusion developer, Helical Fusion still has to prove that it can sustain a burning plasma and extract more electricity than the plant consumes.

Why it matters for overseas partners

• A different technical bet — Most private fusion capital has gone to tokamaks and other concepts. Helical Fusion gives investors exposure to steady-state helical designs backed by decades of Japanese data.
• Supply chain opportunities — Its programme needs HTS tape, cryogenics, gyrotrons, vacuum systems and remote handling, which opens doors for component suppliers.
• Government alignment — Japan’s national fusion strategy aims to demonstrate power generation in the 2030s, and Helical Fusion is part of the startup group the state is backing.
• Research access — Its close links with NIFS and universities give partners a route into Japan’s fusion research base.

Outlook

Helical Fusion is small next to the best-funded fusion companies in the United States, and its timeline is ambitious. Its advantage is a design that suits continuous power generation and a national research base that has refined that design for more than 25 years. If Helix HARUKA performs as planned, the company will have a strong case for the much larger funding a pilot plant will need.