British experiments could wipe out fusion hurdles

Mast upgrade

Artwork: Mast Upgrade is testing an innovative design

According to experts, the first results of the UK experiment could help clear the hurdles for achieving commercial power based on fusion.

Researchers believe there is a way to get rid of the excess heat generated by the fusion reaction.

This intense heat can melt the material used in the reactor and limit the amount of time it can react.

The system, likened to car exhaust, has reduced heat by a factor of 10.

The test was conducted in a mast (Mega Ampere Spherical Tokamak) upgrade fusion experiment in Culham, Oxfordshire. The £ 55m device went live in October last year after seven years of build.

Fusion is an attempt to replicate the process of powering the Sun (and other stars) here on Earth.

Elusive goals

But the trick is to get more energy out of the reaction than you put in. This goal continues to flee a team of scientists and engineers around the world working to achieve fusion capabilities.

Existing nuclear energy relies on a process called division. In this process, heavy chemical elements are split into lighter elements. Fusion works by combining two light elements to create a heavy element.

One of the common fusion approaches uses a reactor design called a tokamak. This design uses a strong magnetic field to control the charged gas (or plasma) inside the donut-shaped vessel.

Vacuum container, mast upgrade

Inside the tokamak where the plasma is controlled by a magnetic field

An international fusion megaproject called Iter is currently under construction in southern France. Professor Ian Chapman, CEO of the United Kingdom Atomic Energy Agency (UKAEA), said it was important to demonstrate the potential to bring fusion power to the grid.

But he added that the size and cost of Iter means that “if you need to raise that amount each time you build a unit, market penetration is determined by economics, not technology.”

“Hotter than the sun”

Mast upgrade is one attempt to devise a more compact and inexpensive fusion reactor template. Utilizing an innovative design called a spherical tokamak, fuel is narrowed down to a 3m wide device.

But this comes at a price. “We make small quantities of things that are hotter than the sun, and how we release the heat is a big challenge,” says Chapman.

Without an exhaust system that can handle this intense heat, the materials in the design would need to be replaced on a regular basis. This has a significant impact on the uptime of the power plant.

The new exhaust system being tested at Culham is known as the Super-X Divertor. This will make future commercial tokamak components much longer lasting. It will significantly improve the availability of power plants, improve their economic feasibility and reduce the cost of fusion energy.

Tests with a mast upgrade have shown that using the Super-X system reduces the heat of the material by at least a tenth.

Researchers said the result was a “game changer” to the promise of fusion power plants that could provide efficient electricity at an affordable price. Against the backdrop of climate change, fusion has the potential to provide a clean and virtually endless source of energy.

Dr. Andrew Kirk, Chief Scientist for Mast Upgrade, said the result was “a moment our team at UKAEA has been working on for almost a decade.”

“We built a mast upgrade to solve the exhaust problem of a compact fusion power plant, but there are signs of success.

“Super-X reduces the heat of the exhaust system from the level of the torch lamps to the levels found in car engines, which means that they need to be replaced only once during the life of the power plant. There is a possibility.”

The success of the mast upgrade exhaust system will support the planning of a British prototype fusion power plant called Steppe. It will be online in the 2040s.

The mast upgrade facility will have an official opening ceremony on Wednesday. There, an honorary guest, Astronaut Tim Peake, will perform a plasma test on the machine to create his own artificial star.

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