Scientists have just broken the record for plasma pressure – the key ‘ingredient’ for fusion, bringing us one step closer to clean fusion energy.

“This is a remarkable achievement that highlights the highly successful Alcator C-Mod program at MIT,” said physicist Dale Meade of Princeton Plasma Physics Laboratory, who wasn’t involved in the experiments.

Image credits: Bob Mumgaard/Plasma Science and Fusion Centre

Fusion energy has been touted as a clean energy source for decades, up to the point where many believe it to be a pipe dream. There is no question about fusion’s theoretical feasibility because this happens naturally in stars, but whether we could actually harvest this energy for ourselves is a different story.

Fusion power is the generation of energy by nuclear fusion. Fusion reactions occur when two or several atomic nuclei come close enough for the strong nuclear force pulling them together to exceed the electrostatic force pushing them apart, fusing them into heavier nuclei. For nuclei lighter than iron-56, the process releases heat which can be harvested. But achieving a stable system for fusion energy generation remains far away.

Still, this is a notable landmark. The research team achieved a pressure of 2.05 atmospheres – a 15 percent jump over the previous record of 1.77 atmospheres. That might not seem like much, but when you consider that the plasma temperature was 35 million degrees Celsius (63 million degrees Fahrenheit) – over twice as hot as the Sun’s core – it becomes easier to understand why this matters. The device they created sustained fusion for 2 seconds, producing a total of 600 trillion fusion reactions.

These three variables, temperature, pressure, and time are considered to be a trade-off. You can have high temperatures for a long time, but not at high pressures, and so on. But pressure has proven to be especially difficult to achieve under these conditions.

The record was achieved at the Alcator C-Mod reactor at MIT, which unfortunately will reach the end of its life after 23 years. Funding is being moved to the ITER machine being constructed in France. Right not, existing fusion machines still consume more energy than they produce, but it is hoped that ITER could become the first sustainable fusion machine in the world, paving the way for clean and virtually limitless energy.

If you have any more questions or anything you’d like to learn about this technology, the researchers behind it will be hosting a Reddit AMA on October 20.