Artron energy was a form of ambient radiation that existed in the time vortex, (AUDIO: Shield of the Jötunn) later described by the Seventh Doctor as a form of mental energy, (PROSE: Timewyrm: Apocalypse) "artron particles" (AUDIO: Shockwave) that could be utilised in a variety of ways. Those who travelled through the vortex would absorb artron energy in the form of a "background radiation." Some life forms were even made of artron energy.