Chronon energy or chronon radiation (also known as time energy) was a form of radiation that was linked to temporal anomalies.
TARDISes released chronon energy (PROSE: Attack of the Snowmen) and Magnus Greel's arrival in the time cabinet in the 1800s via a zygma beam caused massive discharges of chronon radiation which flowed along the Earth's telluric currents, forming the Dragon Paths.
The segments of the Key to Time were traced by the chronon radiation they gave off. (PROSE: The Shadow of Weng-Chiang)
Similarly, those who travelled through time were left with traces of chronon energy, even if the travel was brief. (PROSE: Attack of the Snowmen)
The Vist were capable of "smelling" time energy. (AUDIO: The Forbidden Time)
Time Lord bodies were apparently sustained by chronon energy, as the Sixth Doctor was weakened to the point of death when most of his chronon energy was lost during his confrontation with the Lamprey. (PROSE: Spiral Scratch)
The Ninth Doctor could smell it in the air, describing the scent as "bananas and ice cream". (COMIC: The Bidding War)
Weeping Angels fed on time energy. (TV: Blink, The Time of Angels/Flesh and Stone, The Angels Take Manhattan)