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How does inertial confinement fusion use lasers to compress fuel pellets?

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laser-activated fusion — nuclear fusion Interior of the U.S. Department of Energy's National Ignition Facility (NIF), located at Lawrence Livermore National Laboratory, Livermore, California. The NIF target chamber uses a high-energy laser to heat fusion fuel to temperatures sufficient for thermonuclear ignition. The facility is used for basic science, fusion energy research, and nuclear weapons testing.

In inertial confinement fusion (ICF), lasers are used to compress a tiny fuel pellet to extreme densities and temperatures. The process relies on the following mechanisms:1

Ablation and Implosion: The laser beam ionizes the surface of the multilayered pellet. The resulting ablation of material creates a powerful inward force, causing the inner layers to implode at speeds of several hundred kilometers per second.1
Shock Wave Compression: This implosion generates shock waves that compress the fuel to 1,000 to 10,000 times its solid density.12
Uniformity Methods: To ensure successful ignition, the energy delivery must be highly symmetric. This is achieved via:
- Indirect Drive: The laser targets the walls of a hohlraum, which then radiates the pellet with uniform X-rays.1
- Direct Drive: Multiple laser beams are precisely aimed directly at the pellet to deliver energy uniformly.1

Once compressed, the fuel reaches temperatures sufficient to initiate a fusion burn before the pellet disassembles.12