LEVITATING DIPOLE FUSION | COVER STORY


disappeared from the commercial conversation. The physics remained promising, but the materials needed to scale it did not yet exist at production levels. The commercialisation of rare-earth barium copper oxide (REBCO) superconductors changed that. Earlier superconducting materials required extreme cooling and could not generate the field strengths needed for a commercial machine and the Nobel Prize-winning work by Bednorz and Muller in 1987 paved the way. REBCO operates at higher temperatures than its predecessors and produces stronger magnetic fields, making it possible, for the first time, to contemplate scaling the levitated dipole to power plant size. Dr Darren Garnier, who served as chief experimentalist on LDX, joined OpenStar as chief science officer in 2023, bringing decades of knowledge back to the concept. Suddenly, fusion wasn’t 30 years away, but an imminent reality.


A different confinement approach The levitated dipole belongs to the magnetic confinement family of fusion concepts, alongside tokamaks and stellarators. Those approaches use external coil arrangements housed on the outside of the vacuum vessel to generate the fields that hold plasma in place, imposing order on plasma that constantly seeks to escape. The levitated dipole is essentially the inverse. A single superconducting toroidal magnet is levitated inside the vacuum chamber, generating a dipole field analogous to planetary magnetospheres. The geometry produces a phenomenon known as the turbulent inward pinch: rather than scattering particles outward, turbulence in the plasma drives them inward, self-organising into the peaked, high-density pressure profiles that fusion requires. This physics produces several properties of


commercial relevance. The plasma is inherently stable, meaning there is no risk of disruptions or events where the plasma becomes rapidly unconfined. The vacuum chamber and core magnet are also decoupled, making maintenance straightforward. Furthermore, the concept naturally operates at high beta, meaning a high ratio of plasma pressure to magnetic pressure, implying more fusion output per unit of field strength and, in principle, a more compact and cost-effective machine.


The power supply solution A unique engineering requirement of the levitated dipole is powering a freely levitating superconducting magnet with no external electrical connections. A superconducting coil requires continuous current to maintain its field, and running power leads to a levitating object surrounded by 150,000,000°C plasma is not possible. LDX and RT-1 each solved this differently: LDX charged its magnet inductively before levitation and then let the current in the magnet slowly decay throughout operation whereas RT-1 used current leads in the docked position, with measured current decay of 0.9% per eight-hour levitation period due to finite joint resistance. Both were landmark experiments that advanced the physics of the levitated dipole significantly, but neither was designed with commercial energy production in mind. OpenStar’s solution is an on-board high-temperature superconductor (HTS) power supply consisting of a superconducting transformer-


rectifier circuit mounted directly on the levitating magnet assembly, capable of maintaining and adjusting the magnet current during levitation. The technology was adapted from work done by OpenStar CEO Dr Ratu Mataira, during his PhD on HTS power supplies for hybrid-electric aircraft applications at Paihau–Robinson Research Institute in Wellington. OpenStar maintains strong ties with the institute, employing several alumni and collaborating formally across multiple disciplines, a relationship that has been instrumental in the company’s development. The company’s prototype, Junior, is a 5.6T REBCO


dipole magnet housed inside a 5.2-metre vacuum vessel. Junior achieved first plasma in supported configuration in late 2024, the results of which are covered in their first peer-reviewed paper, and fully levitated plasma in early 2026. The machine was built and commissioned in under two years at a cost below $10m.


A multi-machine development pathway OpenStar has structured its programme around multiple successive machines, each intended to generate commercial value and engineering data in advance of the next. Junior is the first machine and has completed its primary objectives: validating the integration of the HTS power supply into a fully levitated core magnet and proving a viable path to commercial scale. The second, Tahi, will be built in a new facility made possible by the NZ$35m Regional Infrastructure Fund loan announced in February 2026. Tahi’s mission is to produce medical isotopes and


generate early revenue to support development of future machines. Its more powerful magnet and enhanced plasma performance will advance plasma density, temperature, and energy confinement time toward commercially relevant values, and characterise the confinement scaling properties that underpin the subsequent machine designs. Central to this is the development of a significantly more powerful magnet prototype, with Tahi’s core magnet reaching 20T compared to Junior’s 5.6T. The parameters of this and other upgraded systems will directly inform the design of future machines. The third machine, Māui, will operate as a volumetric


neutron source (VNS) whereby target materials are bombarded with a steady-state 14.1 mega-electronvolt (MeV) neutron flux from deuterium-tritium (DT) fusion, transmuting them into high-value products. A larger, more powerful machine capable of greater isotope


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Junior, is a 5.6 T REBCO dipole magnet housed inside a 5.2-metre vacuum vessel.


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