COVER STORY | LEVITATING DIPOLE FUSION
OpenStar has two DT-compatible power plant designs of Tama Nui which machines will be used for energy generation and draw on findings from its Māui device.
full-scale engineering data that Tama Nui, an electricity generating device, requires. This includes neutron flux characterisation, magnet lifetime under irradiation, shielding performance, and thermal management, before a single electron reaches the grid.
production it will achieve Q>1 fusion (net positive). Technically a separate machine, it shares the same architecture as Tahi, just configured slightly differently. Māui is targeting commissioning in 2030, with medical radioisotopes as its primary commercial application. Clinically, radioisotopes are used in life-saving cancer
Key features of the levitated dipole design.
therapies, and demand is growing faster than supply can meet it. Global medical radioisotope production is concentrated in a small number of ageing fission research reactors, the majority approaching or past their operating licence limits. Replacement infrastructure is not arriving in time. Major pharmaceutical companies have collectively invested more than $8bn in radiopharmaceutical supply chain acquisitions since 2023, reflecting both the urgency and the scale of the opportunity. Māui is positioned to fill that gap. Operating without enriched uranium, in a simpler regulatory environment and at a fraction of the capital cost of a fission research reactor, it can be commissioned on a timeline that meets the shortage as it becomes acute. For patients, that means access to treatment. For OpenStar, it means a commercial return that is not contingent on the power plant but rather as the natural consequence of building the right machine at the right time. Māui also serves a parallel development function. Operating as a DT fusion device it will generate the
DT compatibility and the engineering solutions The compatibility of the levitated dipole with DT fuel has been a longstanding question for the concept. DT fusion produces 14.1MeV neutrons, and in the levitated dipole configuration the superconducting core magnet sits inside the plasma, directly in the neutron flux. Prior to OpenStar’s published work, this was perceived as a major obstacle to scaling the concept. The company has two DT-compatible power plant designs of Tama Nui. These machines will be used for energy generation and draw on findings from Māui and addresses the neutron management problem through a layered tungsten and boron carbide shield surrounding the magnet assembly. The shield attenuates the neutron flux to within acceptable limits for REBCO conductors and conducts 92% of the heat it intercepts outward to the first wall, where it is recovered for electricity generation. The REBCO coil is divided into a sacrificial section, approximately 20% of the total conductor volume, designed to reach its neutron damage lifetime in roughly one year, and a larger semi-permanent section with substantially longer service life. Whether for end-of-life replacement or routine maintenance, the entire floating magnet assembly can be removed from the vacuum vessel ex-situ and a replacement installed with minimal downtime. The decoupled geometry of the levitated dipole makes this straightforward and keeps plant availability high, an inherent maintenance advantage. The designs also address onboard cooling. REBCO superconductors must be maintained at cryogenic temperatures, and no external cooling lines can reach the levitating core magnet. OpenStar’s patented approach is an onboard cryogenic reservoir containing a mixture of solid and liquid cryogen. The solid fraction acts as a latent-heat thermal buffer, absorbing heat that would otherwise raise conductor temperature. The conductor remains at operating temperature if any solid fraction remains. When the reservoir is depleted, the magnet docks to replenish it, taking five minutes, during which the vessel retains sufficient thermal mass to continue generating electricity. The two designs achieve 667MW of fusion power and
a predicted 208MWe net at the larger configuration. The core magnet field is 23T, with REBCO conductor strains below 0.4%, within established material limits.
What comes next OpenStar’s immediate focus is the construction of the Tahi facility and continued experimentation with Junior, which will provide further characterisation of the levitated dipole’s confinement properties. The company has so far disclosed around $30m in
private funding, alongside the Regional Infrastructure Fund loan, and has reached its milestones at a pace the broader fusion industry has found difficult to match. With Tahi under development and the engineering case established in peer-reviewed literature, OpenStar is bringing the levitated dipole from the periphery to the forefront of fusion energy. ■
26 | October 2026 |
www.neimagazine.com
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