Artron Energy Capacitor

 was a component within the Doctor's TARDIS. It partly resembled a gigantic metal coil. It could be viewed through a ruby-coloured window, which Ethan Amberglass and Adrian Molecross passed by whilst looking for a way to release Artron energy that was stored within the TARDIS, but had not been released. When the remaining aspects of Sheridan Brett attempted to transfer the capacitor's stored energy to the Equation's dimension, Molecross stepped into the energy field and stopped the transfer, sacrificing himself and destroying what remained of Brett in the process. (PROSE: The Algebra of Ice)