 The original earthbound fusion reactions were created by such a device at the Cavendish Laboratory at Cambridge University.In 1934, Mark Oliphant, Paul Harteck and Ernest Rutherford used a new type of power supply to power a device not unlike an electron gun to shoot deuterium nuclei into a metal foil infused with deuterium, lithium or other light elements.This apparatus allowed them to study the nuclear cross section of the various reactions, and it was their work that produced the 100 keV figure.