Disperser

The Disperser was a piece of technology employed by the Silurians.

This device was capable of dispersing the Van Allen belt around a planet allowing for radiation to directly damage the world thus making it uninhabitable. After the Humans, through the aid of The Doctor, discovered a cure for the Silurian plague, the new leader decided to employ the disperser as a different way of exterminating the Human race.

However, the machine required a great deal of power which they believed they would gain through a Human power station that they were draining power from. (DW: Doctor Who and the Silurians)