Time Vector Generator
A Time Vector Generator was a component of a TARDIS that made it dimensionally transcendental. Removal of the Time Vector Generator would collapse its interior into an alternate dimenion, leaving only the exo-shell and making it the same size on the inside as the outside. It resembled a long ebony wand and was a powerful energy source.
Removal of the TVG turned the inside of the TARDIS shell into an anechoic chamber, which is how the Doctor tricked Atimkos into destroying himself. (PROSE: Invasion of the Cat-People)
The Doctor later removed the TVG when the fluid links exploded, filling the TARDIS with mercury fumes. The TVG was later used to boost Space Station W3's x-ray laser to defeat the Cybermen. (TV: The Wheel in Space)
Jared Khan attempted to steal the TVG from Bernice Summerfield on behalf of his masters, the Charrl. (PROSE: Birthright)