American scientists have announced what they have called a major breakthrough in a long-elusive goal of creating energy from nuclear fusion.
The U.S. Department of Energy said on Dec. 13, 2022, that for the first time – and after several decades of trying – scientists have managed to get more energy out of the process than they had to put in.
But just how significant is the development? And how far off is the long-sought dream of fusion providing abundant, clean energy? Carolyn Kuranz, an associate professor of nuclear engineering at the University of Michigan who has worked at the facility that just broke the fusion record, helps explain this new result.
Fusion is the same process that powers the Sun.
NASA/Wikimedia Commons
What happened in the fusion chamber?
Fusion is a nuclear reaction that combines two atoms to create one or more new atoms with slightly less total mass. The difference in mass is released as energy, as described by Einstein’s famous equation, E = mc2 , where energy equals mass times the speed of light squared. Since the speed of light is enormous, converting just a tiny amount of mass into energy – like what happens in fusion – produces a similarly enormous amount of energy.
Researchers at the U.S. Government’s National Ignition Facility in California have demonstrated, for the first time, what is known as “fusion ignition.” Ignition is when a fusion reaction produces more energy than is being put into the reaction from an outside source and becomes self-sustaining.
The fuel is held in a tiny canister designed to keep the reaction as free from contaminants as possible.
U.S. Department of Energy/Lawrence Livermore National Laboratory
The technique used at the National Ignition Facility involved shooting 192 lasers at a 0.04 inch (1 mm) pellet of fuel made of deuterium and tritium – two versions of the element hydrogen with extra neutrons – placed in a gold canister. When the lasers hit the canister, they produce X-rays that heat and compress the fuel pellet to about 20 times the density of lead and to more than 5 million degrees Fahrenheit (3 million Celsius) – about 100 times hotter than the surface of the Sun. If you can maintain these conditions for a long enough time, the fuel will fuse and release energy.
The fuel and canister get vaporized within a few billionths of a second during the experiment. Researchers then hope their equipment survived the heat and accurately measured the energy released by the fusion reaction.
So what did they accomplish?
To assess the success of a fusion experiment, physicists look at the ratio between the energy released from the process of fusion and the amount of energy within the lasers. This ratio is called gain.
Anything above a gain of 1 means that the fusion process released more energy than the lasers delivered.
On Dec. 5, 2022, the National Ignition Facility shot a…