Novatron Fusion Group powers-up ‘X-Factor’ magnets during N1 prototype tests

Engineers at Novatron Fusion Group are powering-up a revolutionary magnet system – forming a signature piece of the firm’s fusion energy technology - as work rapidly advances on its N1 prototype in Sweden.

Custom made parts and subsystems were carefully assembled throughout 2024 to deliver the ground-breaking reactor at KTH Royal Institute of Technology in Stockholm.

The latest milestone involves test and assembly of a novel magnet system designed to trap plasma fuel within a concave field - bouncing it back and forth like a ball in a mirror-lined room.

The pioneering design simplifies engineering required for a fully operating fusion reactor, allowing the use of conventional copper electromagnets, and replacing ultra-expensive cryogenically cooled superconducting magnets used in alternative tokamak and stellarator designs.

In addition, the concave magnetic field removes the need to ramp up currents to produce stabilising magnetic fields. This allows for higher temperatures than alternative technology.

Thanks to the symmetry of the reactor, and its open magnetic field lines, it is also easier to add fuel and remove by-products continuously during operations – potentially revolutionising the fusion energy process.

“The magnet system is an ‘X-Factor’ within the NOVATRON design,” said inventor and Chief Technology Officer Jan Jäderberg. “The basic idea is to shape the magnetic field in a way where the plasma field is increasing in every direction. It’s the only known concept which features increasing magnetic fields outwards, everywhere in the confinement region.

“This ultimately creates a very high ‘beta value’ – which is a measure of how effectively you use the magnetic field,” added Mr Jäderberg. “Tokamaks typically have a 10% beta value, but we can reach 100%. This means we can use copper magnets to accelerate industrialisation and the scaling-up process, using readily available parts from existing supply chains.”

In preparation for the ‘powering-up’ process, the N1 magnets were tested individually at low power to ensure alignment. Engineers measured their concentricity with millimetre precision.

“The next step involves powering up the magnets in unison - firstly at low power checking the system is working as a whole, including areas such as sensors, coil temperatures and cooling water flow,” added Mr Jäderberg. “We will gradually ramp up to high power in a stepwise fashion until we reach 1000amps per coil. This process will confirm both the magnitude and configuration to ensure we have a correctly shaped magnetic field.”

The N1 prototype is highly versatile, allowing engineers to manipulate many different magnetic fields, ultimately altering the behaviour of the plasma. Pre-calculations have been made to test a total of 25 different settings. Experiments are being run via a PLC using a human-interface touch screen panel to ensure delivery of the correct current, to the correct coils in the correct direction.

“10 months ago, we had nothing but tape on the floor and now we have assembled the N1. It’s been a full team effort, and really the culmination of many years of works,” added Mr Jäderberg. “One very important experiment will involve the creation of the classic mirror configuration to look at the diagnostics and see if its unstable before changing it to the NOVATRON configuration to become stable.”

“It was crucial for our concept to start with an axis symmetric machine,” said Mr Jäderberg. “One is for the plasma. If you divide it from the axis symmetry it makes the plasma unstable which causes other aspects of disruption. Also, from a structural mechanics point of view when you power the coil it creates a very strong magnetic field. With a D-shaped tokamak the force will try and create a circle. If you begin with a circle, it remains the same shape so it’s ultimately a more efficient starting point. There are other fusion developers using axis-symmetric machines, but not combined with an intrinsically stable magnetic field.”

In terms of plant size scalability, the Novatron concept further enables great flexibility in terms of the reactor plasma volume. This enables us to make small plants with superconductive magnets, and very large plants with resistive magnets, ranging from roughly 100MW up to 5GW thermal energy.

“We have also patented the Novatron with super conductive magnets (HTS). Integrating HTS technology allows us to achieve higher pressures, enabling the construction of smaller reactors and utilisation of different fuel cycles - which could potentially revolutionise the whole fusion industry.”

This will cover a large range of applications, from energy consuming industries to cities with tens of thousands of people, up to densely populated regions with tens of millions of people.