LONDON, UK – Scientists in England have set a new record for the quantity of energy generated during a controlled, sustained fusion reaction. The creation of 59 megajoules of energy over five seconds at the Joint European Torus – or JET – experiment in England has been dubbed a “breakthrough” by certain media organizations and has sparked physicists’ interest. However, a frequent saying about fusion energy generation is that it is “always 20 years away.”
We are a nuclear physicist and a nuclear engineer working to develop controlled nuclear fusion for power generation.
The JET finding represents significant progress in the understanding of fusion physics. But, perhaps more crucially, it demonstrates that the new materials used to create the fusion reactor’s inner walls performed as expected. The fact that the new wall structure functioned so well sets these findings apart from past milestones and brings magnetic fusion closer to reality.
Nuclear fusion is the merging of two atomic nuclei into one compound nucleus. This nucleus then breaks apart and releases energy in the form of new atoms and particles that speed away from the reaction. A fusion power plant would capture the escaping particles and use their energy to generate electricity.
There are a few different ways to safely control fusion on Earth. Our research focuses on the approach taken by JET – using powerful magnetic fields to confine atoms until they are heated to a high enough temperature for them to fuse.
The fuel for current and future reactors are two different isotopes of hydrogen – meaning they have the one proton, but different numbers of neutrons – called deuterium and tritium. Normal hydrogen has one proton and no neutrons in its nucleus. Deuterium has one proton and one neutron while tritium has one proton and two neutrons.
For a fusion reaction to be successful, the fuel atoms must first become so hot that the electrons break free from the nuclei. This creates plasma – a collection of positive ions and electrons. You then need to keep heating that plasma until it reaches a temperature over 200 million degrees Fahrenheit (100 million Celsius). This plasma must then be kept in a confined space at high densities for a long enough period of time for the fuel atoms to collide into each other and fuse together.
