OpenStar Technologies, a fusion energy startup, is the only company that tries to replicate the sun’s structure by having a powerful magnet, known as the reactor’s most important component, float in a vacuum, surrounded by a ball of thermonuclear gas.
In their efforts, the startup has achieved the first plasma, a cloud of ionized helium contained by a superconducting magnet suspended at the center of a prototype device called Junior, in New Zealand.
Currently, many fusion energy startups talk about trying to replicate the awesome power of the sun. To do that, they normally use a traditional doughnut-shaped tokamak reactor with magnets outside the reactor to shape the plasma inside, but this plasma configuration is notoriously difficult to create and maintain.
On the other hand, OpenStar’s idea uses a dipole magnet, being common in nature, at the center of the reactor instead. One of the dipole’s big advantages is that they are naturally stable which could potentially open the door to sustained fusion reactions.
However, OpenStar’s founder and CEO Ratu Mataira admitted that although the new design solved a lot of complications by moving to the dipole, it also made the magnet look significantly harder to do.
Placing a superconducting magnet requires chilling to a few tens of degrees above absolute zero amid a fusion reaction at 175 million °C. However, convection in the plasma will drive heat outward toward the reactor walls, instead of inward toward the magnet.
In the newest experiment, the magnet was precooled to about 30 kelvins (-240 °C) and given an 80-minute window until it warmed up and could no longer provide the necessary magnetic field. According to OpenStar, the magnet will have onboard cooling from liquid helium to extend that duration, but it will need to be shut down periodically to be cooled again.
There are other limits to Junior’s operation as the reactor operates that will make the magnet gradually lose energy. Future versions of the central unit will need to contain batteries to extend the life of the magnet.
OpenStar still needs years to produce fusion, but the design includes a magnet hovering meters above the ground, which might be humanity’s best shot at achieving commercial-scale fusion energy.
