On December 5, scientists at the laboratory’s National Ignition Facility (NIF) achieved a “scientific energy breakeven,” otherwise known as ignition.” This means that after bombarding a pellet of frozen deuterium and tritium with laser beams, more energy was produced than went into generating the fusion reaction in the first place.
“The pursuit of fusion ignition in the laboratory is one of the most significant scientific challenges ever tackled by humanity,” LLNL Director Kim Budil says in a press statement. “Crossing this threshold is the vision that has driven 60 years of dedicated pursuit.”
There are many ways scientists are exploring how to power the world with nuclear fusion. The most familiar method involves stellarators or tokamaks, donut-shaped reactors that trap superheated hydrogen plasma so hot it can even damage the reactor in magnetic confinement until their nuclei fuse, flinging neutrons outward and producing energy. However, NIF’s approach, called “inertial confinement,” is radically different and uses lots and lots of laser beams—192 of them to be precise.
Scientists power up and shoot these beams at a cylinder that’s about the size of a pencil eraser. Inside that cylinder is a pellet of deuterium and tritium (which both fuse at lower temperatures and produces more energy) that subsequently implodes. As the hydrogen with helium fuses, it produces energy. For more than a decade, this power transfer—or the amount of energy needed to induce this fusion—exceeded the energy extracted from the experiment. That is, until this week. According to the U.S. Department of Energy, NIF scientists produced 3.15 megajoules (MJ) out compared to the 2.05 MJ of energy put in. For some context, about 3 megajoules can power a one-kilowatt microwave oven for about an hour.
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