Shield oscillator

Shield oscillators were mechanisms that protected spaceships from magno-grabs. The Doctor's TARDIS had one, and the Eleventh Doctor once disabled it in order to allow Clara Oswald to fly the TARDIS. Coincidentally, at that moment, the ship was attacked by a magno-grab, and the TARDIS was consequently destroyed. These events were later negated by the Doctor. (TV: Journey to the Centre of the TARDIS)

References in invalid sources
While remembering instructions from her Type 40 Operational Handbook, Christel Dee disabled the etheric beam locator, shield oscillator, and the food machine, then diverted 'all the power' to the temporal Glowstone stabilisers and the Netherrack Thermocouplings, before declaring 'yes!' and landing. (NOTVALID: Doctor Who Minecraft)