A starship's warp engine relies on three materials to operate: slush deuterium (matter), anti-deuterium (antimatter), iron-infused dilithium (the dilithium crystal). Deck 9 provides storage for the first material, slush deuterium. The radioactive deuterium is kept at extremely low temperatures, and when needed, is injected into the upper segment of the Warp Core for reaction with antimatter to form warp plasma.