The breakthrough in reactor walls has made nuclear fusion possible. This engineering advancement is paving the way for future reactors.
England’s scientists have established a new record in terms of the amount of energy produced by a sustained, controlled fusion reaction. Certain media outlets have called the “breakthrough” creation of 59 megajoules (of energy) at the Joint European Torus experiment in England, or JET, a “breakthrough”. It has also sparked interest among physicists. But, it is still HTML20 years away.
We are both a nuclear scientist and a Nuclear engineer who work to develop controlled nuclear Fusion for power generation.
This JET discovery represents significant progress in understanding fusion physics. It also shows that the inner walls of the fusion reactor were constructed using new materials. These findings are more important than any previous milestones, and bring magnetic fusion closer.
Fusion of particles
The merging of two atomic nuclei to create a single compound nucleus is nuclear fusion. The nucleus is then broken down and released energy as new atoms or particles. This accelerates the reaction. The fusion power plant would use the energy from these particles to create electricity.
There are several ways to safely manage fusion on Earth. Our research is focused on JET’s approach to fusion control. JET uses strong magnetic fields to confine the atoms so that they can fuse at a sufficiently high temperature.
Two different hydrogen isotopes, deuterium or tritium, are the fuel for future and current reactors. They each have one proton but differing numbers of neutrons. Normal hydrogen contains one proton, but no neutrons within its nucleus. Deuterium contains one proton, one neutron, and tritium one proton, two neutrons.
To make a fusion reaction successful, the fuelatoms must first get so hot that electrons can break free of the nuclei. Plasma is a mixture of electrons and positive ions. The plasma must then be heated until it reaches temperatures of over 200 million degrees Fahrenheit (100 millions Celsius). The plasma should then be kept at high temperatures for a sufficient time to allow the fuel molecules to collide with each other and fuse.
Researchers created donut-shaped devices , which contain plasma using magnetic fields. The magnetic field lines that wrap around the donut’s interior act as train tracks, which the electrons and ions follow. It is possible to heat the plasma and inject energy into it, causing the fuel particles to collide. Instead of bouncing off one another, the fuel nuclei fuse. They release energy , mainly in the form fast-moving neutrons.
Fuel particles eventually fall away from the dense, hot core of the fusion reactor and collide with its inner wall. These collisions can cause the walls to become weaker, which can also lead to contamination of the fusion fuel. Reactors are designed so that the wayward particles are directed toward the divertor, a chamber with a heavy armored interior. The divertor pumps out the particles and removes heat from the tokamak.
The first consideration is the divertor wall. The divertor wall is the first consideration. Although the fuel particles are cooler when they reach it , they still have enough energy to knock the atoms out of the wall material of its divertor when they collide with them . The wall of JET’s divertor was made of graphite. However, graphite traps and absorbs far too much fuel to be practical for use.
JET engineers upgraded the divertor’s inner vessel walls to tungsten in 2011. Tungsten was chosen for its highest melting point – an important property when the divertor will likely experience heat loads nearly 10x higher than the nose cone on a spaceship returning to Earth’s atmosphere. The inner vessel wall was made from beryllium and graphite. The thermal and mechanical properties of beryllium are excellent for a fusion reactor. It absorbs less fuel but can still withstand high temperatures .
Although the energy JET generated was the main focus of media attention, we believe it was the use of new wall materials that made the experiment stand out. Future devices will require these stronger walls to sustain high power for longer periods. JET is a proof of concept that shows how to build the next generation fusion reactors.