Fusion is a natural phenomenon that provides our planet with much of its energy—generated millions of miles away in the center of our sun.
Here on Earth, scientists are trying to replicate the hot and dense conditions that lead to fusion. In the center of a star, gravitational pressures and high temperatures—around 200 million degrees Fahrenheit—energize and squeeze atoms close enough together to fuse their nuclei and generate excess energy.
"The end goal of fusion research is to reproduce a process that happens in stars all the time," says Arianna Gleason, staff scientist at the Department of Energy's SLAC National Accelerator Laboratory. "Two light atoms come together and fuse to form a single heavier, more stable nucleus. As a result, excess mass—the one nucleus has less mass than the two that formed it—is converted to energy and carried away."
That leftover mass (m) becomes energy (E) thanks to Einstein's famous E=mc2 equation. Getting fusion to happen on Earth is surprisingly simple—and has been achieved many times over the past few decades using a wide range of devices. The hard part is to make the process self-sustaining, so that one fusion event drives the next to create a sustained, "burning plasma" that could ultimately generate clean, safe and abundant energy to power the electric grid.
"You can think of this like the striking of a match," explains Alan Fry. project director for SLAC's Matter in Extreme Conditions Petawatt Upgrade (MEC-U). "Once ignited, the flame keeps burning. On Earth we have to create the right conditions—very high density and temperature—to get the process to happen, and one of the ways to do that is with lasers."
Enter inertial fusion energy, or IFE, a potential approach to building a commercial fusion power plant using fusion fuel and lasers. IFE has garnered increased national support since scientists at Lawrence Livermore National Laboratory's (LLNL) National Ignition Facility (NIF) have repeatedly demonstrated fusion reactions that produced a net energy gain for the first time anywhere in the world.
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