direct drive is the form of 📝inertial confinement fusion (ICF) in which laser beams strike the fuel capsule directly, rather than first heating a surrounding cavity that re-radiates their energy as X-rays.
Its near-neighbor is indirect drive, the scheme in which the beams instead heat a 📝hohlraum enclosing the capsule, and the two divide the field along a single trade: coupling efficiency against illumination symmetry. Direct drive delivers several times more of the laser's energy into the capsule, because no intermediate X-ray conversion step bleeds it away — an advantage that compounds in any future power plant, where every joule of drive must be paid for in electricity. The price is precision: with nothing to smooth the drive, any nonuniformity in the beams imprints directly on the capsule surface and seeds Rayleigh-Taylor instabilities that can tear the implosion apart, so direct-drive experiments lean on beam-smoothing techniques and exacting target finishes.
The approach's principal home is the OMEGA laser at the University of Rochester's Laboratory for Laser Energetics, the largest facility configured for direct drive, while the National Ignition Facility — which achieved 📝ignition in 2022 — was built around indirect drive. Which scheme better scales to inertial 📝fusion energy remains an open question in the field.