The goal of inertial confinement fusion is to swiftly heat and compress small capsules of hydrogen fuel with a powerful laser. Ideally, the implosion is spherically symmetric: Hydrogen fuses into helium and emits alpha particles, which slam into more hydrogen and trigger a sustained fusion reaction. In practice, however, Rayleigh–Taylor instabilities subvert spherical symmetry. Barely perceptible bumps on the capsules or variations in laser intensity get magnified as the fuel implodes and create fractures through which the hot, dense plasma needed to drive the reaction escapes.
Now an international team of physicists using the OMEGA laser at the University of Rochester in New York has reduced Rayleigh–Taylor instabilities with the help of extremely low-density foam. The researchers spread the foam over a thin sheet of foil (see image below), which served as the target in place of a fuel capsule. Once struck by six 500-joule beams, the foam vaporized instantaneously...
