Hypermatter

Hypermatter is an exotic material used for high-capacity power generators in Star Wars.

EU Technobabble Details

Hypermatter is tachyonic matter that exists in hyperspace . When constrained by realspace, charged tachyons are annihilated as they accelerate to infinite speed within a reactor. The hyperdrive adjusts the faster-than-light hypermatter particles to allow a ship to jump to light-speed without changing its complex mass and energy.