[FarCenter]

Typically deuterium or tritium is used in fusion experiments. Deuterium is extracted from water. Tritium is made in fission reactors by neutron activation of lithium 6.

[Nateman]

Deuterium is 0.0145% of the Hydrogen population. Your average proton will bounce around for over a billion years in the suns core before it becomes Deuterium . Once it succeeds in becoming Deuterium it only lasts a few seconds before it becomes something else. Because of this I find it amazing that most of the Deuterium in the Universe was made in the Big Bang .