 Oliphant used electromagnetic separation to separate the isotopes of lithium . He was the first to experimentally demonstrate nuclear fusion . He found that when deuterons reacted with nuclei of Helium @-@ 3 , tritium or with other deuterons , the particles that were released had far more energy than they started with . Binding energy had been liberated from inside the nucleus . Following Arthur Eddington 's 1920 prediction that energy released by fusing small nuclei together could provide the energy source that powers the stars , Oliphant speculated that nuclear fusion reactions might be what powered the sun . With its higher cross section , the deuterium – tritium nuclear fusion reaction became the basis of a hydrogen bomb . Oliphant had not foreseen this development : 
