00:00 U.S. scientists have repeated what appears to be an energy breakthrough - a nuclear fusion
00:06 reaction that gave off more energy than went into it for a second time after months of
00:12 near misses.
00:14 Fusion is a reaction that takes place in the sun, and it's hoped replicating that could
00:18 one day lead to a source of near-limitless and clean energy.
00:23 Scientists at the California-based Lawrence Livermore National Laboratory say they repeated
00:27 the feat in an experiment in late July, after they achieved it first in December using lasers.
00:34 But this time, a lab spokesperson said the scientists were able to produce an even higher
00:39 energy yield, but that final results are still being analyzed.
00:44 The experiment is trying to replicate fusion through so-called nuclear ignition.
00:49 It involves focusing a laser on a target fuel to fuse two lighter atoms, such as hydrogen,
00:55 to form heavier elements, and in the process, release a burst of energy.
01:00 The December trial generated around three megajoules of energy output after the laser
01:05 delivered a little over two megajoules to the target.
01:08 The U.S. Energy Department called it a "major scientific breakthrough decades in the making,"
01:14 adding it will pave the way for advancements in national defense and the future of clean
01:18 power.
01:20 While experts outside the lab have applauded the advancements since December, they told
01:24 Reuters much more work is needed to make fusion power commercially viable.
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