Researchers are one step closer to a safer and cleaner energy free from carbon dioxide emissions.

A team from Chalmers University of Technology in Sweden have created a new method of decelerating runaway electrons, paving the way for better fusion power.

To get atoms to combine requires both high pressure and high temperatures, but runaway electrons also are a danger to fusion reactors. An unwanted electric field could jeopardize the entire process because electrons with extremely high energy can suddenly accelerate to high speeds that can destroy the reactor wall.

However, a pair of plasma physicists from Chalmers have successfully identified the runaway electrons and decelerated them, by injecting heavy ions in the form of gas or pellets, including neon and argon.

When electrons encounter resistance and lose speed they collide with the high charge in the nuclei of the ions. The collisions make the speed controllable and enables the fusion process to continue.

The researchers were able to use mathematical descriptions and plasma simulations to predict the electrons’ energy and how it changes under different conditions.

“When we can effectively decelerate runaway electrons, we are one step closer to a functional fusion reactor,” doctoral student Linnea Hesslow, said in a statement. “Considering there are so few options for solving the world’s growing energy needs in a sustainable way, fusion energy is incredibly exciting since it takes its fuel from ordinary seawater.”

There are currently no commercial fusion power plants, but researchers believe it is in the cards in the near future.

“Many believe it will work but it’s easier to travel to Mars than it is to achieve fusion,” Hesslow said. “You could say that we are trying to harvest stars here on earth and that can take time.

“It takes incredibly high temperatures, hotter than the center of the sun, for us to successfully achieve fusion here on earth,” she added. “That’s why I hope research is given the resources needed to solve the energy issue in time.”

Fusion energy—created when light atomic nuclei is combined using high pressure and temperatures of about 150 million degrees Celsius—is considered a much safer alternative to nuclear power, which is based on the splitting of heavy atoms. A fusion reactor stops the entire process and grows cold when something goes wrong, eliminating the risk of the surrounding environment being affected.

Fusion reactors also use fuel that weighs less than a stamp and raw materials that come from seawater.

However, fusion reactors have yet to be able to produce more energy than they are supplied.

The study was published in Physical Review Letters.