To create these, a stream of negative muons is sent onto blocks of protium, deuterium and tritium (3 first isotopes of hydrogen). The muon bumps out the electron in the hydrogen atom. Because the electron is replaced, any 2 atoms are bound together. This makes a molecular ion, also called a special muonic molecule. A muon is 207 times more massive then an electron. Because of the difference in mass, the atom changes. Because it is heavier, the atoms in the molecular ion are pressed very tightly together, and then the nuclei, the centers of the atoms, join together. The following process is called nuclear fusion. The 2 nuclei join together and "glue" together. But, their weights do not just add up, a part of their mass is released as energy. This is the energy used. 