OpenStar levitates 550kg fusion magnet in NZ demo with plasma milestone

OpenStar engineers position the Junior prototype’s 550 kg REBCO magnet during assembly in the Lower Hutt facility, ahead of its recent levitated plasma demonstration.

(Image courtesy of OpenStar)

Wellington-based startup OpenStar Technologies has floated a 550 kg superconducting magnet inside a cloud of superhot plasma, with New Zealand Prime Minister Christopher Luxon triggering the sequence that kept it airborne for roughly 20 seconds. All Blacks legend and Icehouse Ventures investor Richie McCaw was also in the room at the Lower Hutt facility.

The magnet is the heart of Junior, OpenStar’s levitated dipole experiment. It runs a 5.6 T REBCO high-temperature superconducting dipole cooled to between 30 and 50 K, stores 0.5 MJ of magnetic energy, and is built to handle 74 tonnes of compressive force trying to implode it. Plasma heating comes from less than 50 kW of electron cyclotron resonance. None of that is what makes the demonstration interesting. What matters is that the magnet floated freely, powered by an onboard HTS flux pump that maintains current during levitation without any physical connection to the outside world. Full operating current is 1,440 A; the system has been run at partial strength so far.

OpenStar first achieved plasma with the magnet mechanically supported in late 2024. The latest campaign added the levitation, and that distinction matters more than it might sound. Once the magnet is tethered, the field lines wrap around mechanical supports and the plasma behaviour the levitated dipole concept actually promises never materialises. Remove the tether and particles can zip along unobstructed field lines in ways that, in theory, naturally suppress the turbulence that plagues tokamaks. The scientific precedent is the LDX experiment at MIT and Columbia, which shut down in 2014. Junior is essentially LDX rebuilt with second-generation HTS tape and a flux pump small enough to ride along for the trip.

No confinement time, beta values, or Lawson parameters from the levitated runs have been published yet. The plasma temperatures Junior is achieving are well below anything fusion-relevant. That is not the point of this machine. Junior’s job is proving that the flux pump integration works at scale and that the levitation control system is reliable enough to build on. By that measure, the recent demonstration was a success.

The arXiv paper documenting the design and early results was published in August 2025. The New Zealand government’s $35 million infrastructure commitment, announced alongside the levitation milestone, funds the facility needed for Tahi, the follow-on device OpenStar says will place a levitated dipole on the Lawson criterion curve for the first time. OpenStar grew out of Victoria University of Wellington’s Robinson Research Institute and has roughly 70 people working on an approach most of the fusion industry stopped paying attention to a decade ago.

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