Powering a floating magnet - a PhD opportunity at the leading edge
'Superconducting magnetic-switch rectifier for fusion-magnet flux pump', has been selected for the inaugural Applied Doctorates Scheme, a Ministry of Business, Innovation and Employment (MBIE) initiative with an initial focus on energy. It is a three-year applied doctorate that lives exactly where deep physics, materials science, and a fast-moving industrial goal converge.
In OpenStar Technologies’ production facility, a superconducting magnet levitates inside a large vacuum chamber. There are no thick copper cables running in from outside, no obvious way to deliver the enormous current it needs. It has to be like that – the magnet will eventually be surrounded by a hundred million-degree plasma, generating energy from fusing hydrogen atoms. The power supply has to live inside a tightly controlled, cryogenic world. Solving that problem sits at the heart of a new PhD opportunity shared between Te Herenga Waka—Victoria University of Wellington’s Paihau—Robinson Research Institute and OpenStar.
You can apply here: https://applieddoctorates.nz/projects/
The power to boost fusion
At its simplest, the project is about finding a better way to power very large superconducting magnets. Traditionally, you run high-current copper leads from a room-temperature power supply into a cryogenic magnet. One end of each lead is warm, the other is extremely cold, and heat inevitably leaks along the metal into the cryogenic space. For the enormous currents needed for fusion magnets – tens of kiloamps – that heat load becomes a serious design and cost issue.
'Effectively, what we want is a cryogenic, very-high-current power supply,' says Dr Nick Strickland, principal scientist at Paihau—Robinson. 'A way of boosting a small current into a large one without dragging all that heat in from the outside.'
The device that makes this possible is a flux pump. In broad terms, a flux pump takes a modest alternating current, uses it to generate a much larger alternating current in a superconducting loop, and then converts that into the direct current required to run the magnet. The magnetic-switch rectifier is the clever part of the circuit that performs switching and rectification without relying on conventional resistive electronics, which would waste energy and generate heat.
'We already have the prototype that can do a version of this,' Nick explains. 'The next step is to make the material much more responsive, so we don’t need huge fields to switch it, and the change in behaviour is much stronger.'
Robust science – advanced engineering
Achieving that means either identifying a different superconducting material or deliberately modifying existing conductors, so they still perform well when no field is present but lose superconductivity quickly and predictably when a field is applied. It is a subtle challenge: industry has spent two decades trying to stop superconductors lose performance in magnetic fields, and this project is about teaching them to lose it on demand, in exactly the controlled way.
All of this has to work inside OpenStar’s distinctive architecture: a levitating superconducting magnet inside a sealed vacuum chamber, with no opportunity to run conventional current leads through the walls. The flux pump and magnetic-switch rectifier must sit inside the magnet, powered from batteries and operating autonomously.
Super collaboration in a tight partnership with global impact
The collaboration between OpenStar and Paihau—Robinson Research Institute is built on a long, shared history.
Over more than fifteen years, the Institute has developed a range of flux pumps for electric machines and superconducting magnets, and many of the people now driving OpenStar’s technology – including members of its flux-pump team – came from Paihau—Robinson. 'A huge amount of knowledge in this area walked out of our door and landed in OpenStar,' Nick says with a smile. 'Now we’re working together again, with them pulling hard towards a commercial fusion device and us providing the deep material science and underpinning knowledge.'
OpenStar brings urgency, scale, and a very specific target: a compact fusion energy system developed on an aggressive timeline, in step with international leaders. The Institute brings decades of expertise in superconducting materials, magnet design, and characterisation.
‘Industry,’ Nick notes, ‘will generally explore just far enough to find a workable path: Once they’ve got something that works, they have to commit to it and continue to improve incrementally. A university is the place that can keep exploring, make the step-change discoveries, and feed better options back in as the technology matures.’
For New Zealand, this partnership offers an opportunity to engage with a new energy technology that is independent of fossil fuels, weather conditions, or specific geographical locations. Nick highlights that OpenStar’s levitated dipole magnet concept could be particularly suitable for smaller nations: 'You can imagine a New Zealand-sized fusion power station based on this. But of course, the real market is global.’
Not for the faint-hearted
For the PhD candidate, the work naturally divides into two intertwined streams. At Paihau—Robinson, you will begin by carefully measuring how the currently selected superconductor behaves with and without a magnetic field, across a range of temperatures and conditions. From there, you will explore ways to tweak and enhance that behaviour – trying alternative superconductors, altering microstructure, and revisiting some of the older scientific literature that newer researchers may never have had reason to read.
'A lot of the really detailed understanding dates back to the nineties and early 2000s,' Nick says. 'The people who explored that stuff in detail are my age and older, and the knowledge tends to get buried. This is a chance for young scientists to dig some of it back up and do something new with it.'
‘You will spend time learning to use cryogenic measurement systems, precision instrumentation, and analysis tools, with experienced researchers nearby when problems arise,’ explains Nick. That environment is something Nick values highly. 'One of the big differences here is that everyone around you is doing research,' he says. 'Our PhD candidates often say they’re surprised by how much support they get. You’re not left on your own to sink or swim.'
Once promising materials or device concepts emerge, your work shifts more toward OpenStar’s facility, where you will help build and test a demonstrator flux pump that incorporates your improved switching element. ‘You will see the full loop: design, build, measure, reflect, redesign,’ explains Nick - the comprehensive nature of this PhD work.
Not a single boring day
This is not a project for someone who wants to live solely in simulation or solely in the lab. Nick describes the ideal candidate as 'a bit of an all-rounder' with a strong grounding in physics or engineering who is also happy with a soldering iron or a screwdriver.
‘You will write code, run models, and interpret data, but you will also spend time wiring experimental rigs, troubleshooting hardware, and working alongside engineers in a real production environment. 'I’d tell a prospective student over coffee that they won’t be bored,' Nick laughs. 'And at each stage, you know what you’re doing feeds into something very concrete and meaningful.'
Standing on the shoulders of giants to lead the future
For Nick personally, there is a sense of coming full circle. This project connects back to his early work on high-temperature superconductors and magnet design, but in a world where there is now real commercial pull.
Fusion companies are already ordering thousands of kilometres of superconducting wire, and the devices built in the next few years will inform the first generation of commercial power plants.
'For a student starting here, it’s a wonderful opportunity,' he says. 'You can make a small contribution to something that’s massive and moving very fast – and potentially revolutionising the whole energy sector. And if you decide at the end that you love this field, the fusion industry is hoovering up people with these skills.'
He pauses, then adds one more thing that might matter to a prospective candidate: 'Our PhD students can be our future colleagues. It’s like a research apprenticeship: if it’s a good fit – for you and for us – then there are a lot of doors that can open, here at the institute, at OpenStar, or with our colleagues around the world.'