Why our spherical tokamak design holds the key to commercial fusion energyBlog
19 February 2021

Why our spherical tokamak design holds the key to commercial fusion energy

In the 1980s, Tokamak Energy founder Alan Sykes investigated theoretically how squashing up a tokamak from a ring-doughnut to a cored-apple shape would affect its results. He showed that this new type of fusion machine would improve performance and increase stability. Using hydrogen, an abundant natural material found across the world, this compact tokamak could provide a realistic alternative to fossil-fuel-powered energy production. His new design worked, and today forms the basis for our next-generation of commercially-viable fusion technologies that could meet the world’s growing demand for energy while protecting the planet.

At the heart of our unique solution are these spherical tokamaks. They’re more efficient than previous fusion machine designs, and could provide a safe and sustainable way to create and capture the energy of the stars.

Why spherical tokamaks?

Fusion energy offers a safe and sustainable alternative to fossil-fuel powered energy production.

In a tokamak, hydrogen gas is heated to become a ‘plasma’, which is trapped and pressurised by magnetic fields. Energised plasma particles begin to collide. As the particles fuse, they release enormous amounts of energy.

In the 1980s, Alan Sykes and colleagues at the Culham Centre for Fusion Energy and Princeton Plasma Physics Laboratory, USA, discovered that changing the tokamak’s design had a huge impact on its potential and performance.

They proposed a new design known as a spherical tokamak. Instead of a ring doughnut, it looks more like a cored apple.

Today, spherical tokamaks are at the heart of our route to fusion faster—with commercial viability front and centre.

Here are four key advantages of spherical tokamaks over conventional tokamaks:

1. Unparalleled efficiency

In a spherical tokamak, the plasma inside sits closer to the centre of the ring than in traditional designs, meaning that it experiences a higher magnetic field. The compactness of spherical tokamaks means they can achieve higher magnetic pressures, which enables them to achieve higher output powers.

2. Total confinement

Scientists have also established that the innovative spherical tokamak design can keep the plasma inside hotter for longer, which is necessary for fusion reactions to occur. Known as the energy confinement time, the longer plasma can be held at higher temperatures, the more fusion will occur and the more energy can be captured.

3. Exceptional performance

Spherical tokamaks provide greater stability for plasma. This stability means there’s less likelihood of heat loss or leakage, which could reduce production or disrupt operation.

When compared to traditional fusion power, spherical tokamaks can deliver higher levels of performance consistently.

4. Superior stability

The innovative design of a spherical tokamak produces a stabilising current to control the plasma more effectively than traditional techniques. The magnetic fields required to contain the plasma are much smaller too.

This means the tokamak itself requires less energy to operate, making production cheaper and more efficient.

Tried and tested technology

New developments in design and engineering pioneered by Tokamak Energy and the availability of high-performance components, such as high temperature superconductors (HTS) are making affordable fusion a reality.

We’re leading the world in our research, and are a core part of the UK Government’s strategy for leading fusion energy technologies. We also have received backing and support from the US Government to further develop our cutting-edge fusion technologies.

Our compact spherical tokamak, called ST40, is the latest step in our journey to deliver commercially viable fusion power and is expected to achieve fusion temperatures this year.