The 100‐foot‐long electron linac at right is the heart of the new High Explosive Flash Radiography Facility at Livermore. Dedicated in April, the Facility is intended primarily for weapons experiments. It provides extremely intense, ultrashort bursts of highly penetrating x‐ray photons—3×1011four‐to‐five‐MeV photons in 60‐nanosec pulses. Thus it will render high‐time‐resolution x‐ray pictures of the deformation of interior components of nuclear‐warhead mockups during the detonation of their conventional explosives. The requirement that such implosions maintain a high degree of spherical symmetry leads to very demanding tolerances on the weapons components. The x‐ray flash is produced by a 4‐kA beam of 20‐MeV electrons. The accelerator is a ferrite‐core induction linac.