# Deuterium Deuterium is the [[Hydrogen]] [[Isotope]] with a [[Neutron]] alongside its [[Proton]] — twice the mass, the same single electron, and therefore essentially the same chemistry. About one hydrogen atom in 6,400 on [[Earth]] is deuterium, which sounds rare and is not: the oceans hold an effectively unlimited supply. ## Heavy water, and the fusion case Water made with deuterium is heavy water, dense enough to be separated by [[Density|physical]] means and used as a moderator in some reactors. The larger interest is [[Nuclear_fusion]]: deuterium fusing with [[Tritium]] is the easiest reaction to ignite and the basis of [[Magnetic_confinement_fusion]] and [[Inertial_confinement_fusion]] alike. Deuterium fusing with [[Helium-3]] instead is the aneutronic route — harder to light, far cleaner in what it emits, and the reason [[WT!Space_Mining_In_Minnesota|lunar helium-3]] is discussed at all. See [[Aneutronic_fusion]]. **Reads with:** *Future Energy: Opportunities & Challenges (2013)* — [OTL record](https://open.umn.edu/opentextbooks/textbooks/future-energy-opportunities-challenges) · [download](https://trace.tennessee.edu/entities/publication/48577f98-9b67-472e-bbb3-5d150c80c1e2). Seeded from the Thury Hydrodynamics Apex Spine book shelf. **On the spine:** [[Tritium]] · [[Isotope]] · [[Nuclear_fusion]] · [[Helium-3]] · [[WT!Thury_Hydrodynamics_Compendium]]. ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Deuterium) : [Wikitube](https://en.wikitube.io/wiki/Deuterium) ## Previous hub tags Hubs: `Life_Physics`, `Systems`. Portals: [[PORTAL_Thury_Hydrodynamics_Apex_Spine]], [[PORTAL_Hydrogen]], [[PORTAL_Energy]]. --- *Apex Spine wave · 2026-09-10 · stub · microsim layer deferred.*