When the protostar becomes hot enough (7 million kelvins), its hydrogen atoms begin to fuse, producing helium and an outflow of energy in the process.

The minifusion device accelerates hydrogen atoms and slams them together to produce helium.

A first-generation star uses elemental hydrogen (H) as a fuel source and produces helium (He).

In the sun, energy is produced when hydrogen nuclei fuse to produce helium, a heavier element.

The Sun's heat results from the fusion of hydrogen with hydrogen, producing helium, with the release of energy, he explained.

By this stage the quest was no longer simply one of producing helium but also of liberating energy.

Through this time, both helium consumption and the costs of producing helium increased.

"It's because we are producing helium instead."

The temperature required to produce liquid helium is low because of the weakness of the attractions between the helium atoms.

Stars spend about 90% of their lifetime fusing hydrogen to produce helium in high-temperature and high-pressure reactions near the core.