![The fusion reactions at the National Ignition Facility takes place at the heart of the world's most powerful laser system, which consumes about 400 MJ of energy each time it's fired.](https://cdn.mos.cms.futurecdn.net/EhCqqyhRc7VboNiBZnMop8-320-80.jpg)
The secret behind a record-breaking nuclear fusion experiment that spit out 10 quadrillion watts of power in a split second has been revealed: a "self-heating" — or "burning" — plasma of neutron-heavy hydrogen inside the fuel capsule used in the experiment, according to researchers.