Deuterium
- Isotope of hydrogen commonly used as fuel in fusion and warp core reactors
- Occasionally known as "neutronic fuel" due to its extra neutron as compared to hydrogen, especially in older (c.22nd-century) reference material (ENT Novel: Kobayashi Maru; Star Trek II: The Wrath of Khan)
- Connection between "deuterium" and "neutronic fuel" conjecture, based on reference as explosive in Kobayashi Maru
- Most commonly stored and transported in slush form, liquid/solid blend, held at high pressure and low temperature
- Explosive in standard conditions, more difficult to transport due to tank outgassing