The so-called nuclear fusion refers to the process in which two lighter nuclei combine to form a heavier nucleus, a reaction that is the opposite of fission.
For example, the magic fusion reactor they were building this time was created by generating a high-temperature, high-pressure environment that allows the isotopes of hydrogen, deuterium, and tritium to combine and fuse into helium...
Theoretically, as long as there is a sufficiently powerful high-temperature and high-pressure environment, fusion can continue down the periodic table of elements. However, even the high temperatures and pressures at the core of the Sun can only support fusion up to iron.
Other elements, which are heavier and more massive, are usually formed in cosmic spectacles such as supernova explosions and binary star mergings.
