Tokamak Energy's Demo4 powers ahead with cryogenic success

Tokamak Energy's Demo4 system edges closer to practical fusion power as it successfully completes milestone cryogenic tests.
Tejasri Gururaj
Tokamak Energy's Demo4 magnet system
Tokamak Energy's Demo4 magnet system

Stuart White/Tokamak Energy  

Nuclear fusion energy is often considered the epitome of clean and sustainable power. This process is akin to the one that fuels stars in the Universe, and scientists aim to replicate it here on Earth.

However, one of the biggest challenges faced by fusion energy research is achieving the high temperatures and pressures, such as those in the cores of stars, to initiate and sustain nuclear reactions.

However, this challenging goal is now one step closer to realization. In a groundbreaking development, Tokamak Energy's superconducting magnet system, known as Demo4, has successfully completed a crucial series of cryogenic tests.

This achievement is a significant step forward in the field of fusion energy technology.

Demo4: A superconducting magnet system

The Demo4 system was revealed by Tokamak Energy a few months back with the aim of replicating the magnetic fields needed for fusion power plants. The system is capable of carrying a staggering 12 million Amperes (amps) of electricity through its central column.

This remarkable achievement relies on the use of high-temperature superconductors (HTS). These are materials that offer no electrical resistance, making them ideal for generating the powerful magnetic fields required to contain and control the plasma in a fusion reactor.

Their main advantage is that they don't require the supercool temperatures required by typical superconductors, which are very hard to achieve. 

Tokamak Energy's Demo4 powers ahead with cryogenic success
The Demo4 limb test in liquid nitrogen.

The Demo4 system, comprising 44 magnetic coils, is set to operate at a temperature of -423.4 degrees Fahrenheit (-253 degrees Celsius) in a vacuum. The temperatures are maintained using closed-cycle cryocoolers. 

Why cryogenic testing matters

Cryogenic testing evaluates the materials and components at extremely low temperatures, in this case, the HTS magnets of the fusion reactor.

Unlike traditional superconductors, HTS materials operate at higher temperatures, simplifying cooling while boosting efficiency. This testing ensures the fusion system can endure the bone-chilling cold temperatures needed for fusion reactions

For the testing, the team at Tokamak Energy tested a crucial part of their fusion reactor, called the toroidal field (TF) limb, by exposing it to extremely cold temperatures, -328 degrees Fahrenheit (-200 degrees Celsius), using liquid nitrogen. The TF limb is responsible for generating the strong magnetic fields in the reactors. 

This test helped them confirm that the TF limb worked as expected, even in freezing conditions. They also checked how well the different parts of the TF limb were connected and if they allowed electrical current to flow smoothly between them. This successful test is a big step forward in their project.

Speaking of the results in a press release, Dr. Rod Bateman, Tokamak Energy's magnet development manager, said, "These first set of extremely positive results are a major step forward for the Demo4 project, which will allow us to create substantial magnetic forces and test them in fusion power plant-relevant scenarios for the first time."

"A magnet system of this kind has never been built before. We now move forward to the next stage with great confidence in our manufacturing process on the path to delivering clean, secure, and affordable fusion power in the 2030s."