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How does nuclear fusion work?

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Quick answer

Nuclear fusion works by forcing light atomic nuclei — like hydrogen — together under extreme heat and pressure until they merge into a heavier nucleus, releasing enormous energy. It powers the Sun and stars, and scientists are working to harness it on Earth.

Step by step

  1. Light nuclei are fused into a heavier one.
  2. It requires extreme heat and pressure.
  3. It releases vast energy — more than fission.
  4. It powers the Sun and stars.

People also ask

How does nuclear fusion work?
Extreme heat and pressure force light nuclei to merge into a heavier one, releasing huge amounts of energy.
What's the difference between fusion and fission?
Fusion joins light atoms together; fission splits heavy atoms apart.
Why don't we use fusion for power yet?
Sustaining the extreme conditions and getting more energy out than in remains a major engineering challenge.