Warp Coil

In the fictional universe of Star Trek, a Warp Coil is a component of the warp drive. They are also known as warp field coils

Warp field coils are asymetrically placed units that propel the ship into warp flight. Depending on the geometry of the warp field projected around the ship, these coils create a pulsating field when injected with a controlled plasma burst, pushing to the rear of the vessel, propelling the ship forward in a controlled rate.

External Links

Info about the Force of Nature episode at Startrek.com