What is a hydrogen bomb?

A hydrogen bomb, or thermonuclear weapon, uses the energy from a primary fission bomb to ignite a secondary nuclear fusion reaction. The result is the most destructive weapon ever created by man

ATOM BOMB: Compresses core of uranium or plutonium until nuclei of core splits up, releasing huge amount of energy in process called fission

Neutron initiator: Produces burst of neutrons needed to start chain reaction

Uranium or plutonium core: Fissile material

Explosive lenses: Use sphere of detonators to synchronize shock waves to compress core to supercritical mass 

HYDROGEN BOMB: Uses energy from primary fission bomb to ignite secondary
nuclear fusion reaction

Small atom bomb explodes, emitting radiation

X-rays from primary detonation reflect inside casing, heating foam

Foam becomes plasma and compresses secondary package, igniting fusion fuel

Miniaturization: Hydrogen bombs can pack explosive power into smaller, light-weight packages delivered by ballistic missiles

Atom trigger

Polystyrene foam

X-rays

Hydrogen fuel

Uranium tamper

Sources: Federation of American Scientists, Encyclopedia Britannica