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How does inertial confinement fusion use lasers to compress fusion fuel?
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fusion reactor
A tokamak is a device used in nuclear-fusion research for magnetic confinement of plasma.
In inertial confinement fusion (ICF), lasers are used to compress a tiny fuel pellet—typically composed of deuterium-tritium—to extreme densities and temperatures. This process relies on the following mechanisms:1
- Ablation and Implosion: The laser beam strikes the surface of the multilayered pellet, ionizing the material. This causes the outer layer to blow off, or ablate, which generates a powerful inward recoil force. This force implodes the inner layers of the fuel at speeds of several hundred kilometers per second, creating shock waves that compress the fuel to 1,000 to 10,000 times its solid density.12
- Uniformity: To ensure successful ignition, the implosion must be highly symmetric. This is achieved either through direct drive, where multiple laser beams strike the target directly, or indirect drive, where lasers heat the walls of a cavity called a hohlraum, which then bathes the pellet in uniform X-rays.1
- Heating: In conventional shock-heated ICF, the converging shocks heat the pellet's center to fusion temperatures. Alternatively, in fast ignition, a separate, intense laser pulse heats a small portion of the already compressed fuel to initiate the burn.1