Plasma coil
A plasma coil was a component of a starship's engines and of cloaking devices. 

In 2151, shortly before the maiden voyage of , a case of valve sealant was beamed up to the ship instead of plasma coils, to Lieutenant Malcolm Reed's chagrin. ()

In 2153, magnetic containment on Enterprise was fluctuating, due to the Sphere-Builder test subject trying to destroy Enterprise by destabilizing the magnetic seals on the warp core. Malcolm Reed and Major J. Hayes were able to defeat the Sphere-Builder by reversing the polarity of the plasma coils to trigger a feedback pulse. ()

While visiting Deep Space 9 in 2369, Geordi La Forge was interested in purchasing a 21st century Ktarian plasma coil that he found in a shop on the Promenade in near perfect condition. ()

In 2370, Data initialized the plasma induction coils on an infusion unit while in a cave on Atrea IV trying to stop the cooling of the planet's molten core. ()

In an unknown, future timeline, the  took a hit to its starboard plasma coil from the Klingons, which damaged the ship's cloaking device. Admiral William T. Riker had the Enterprise taken back to Federation space at warp 13, without the cloak. ()

Loose plasma coils created large amounts of radiation. A Bajoran transport docking at Deep Space 9 in 2371 had a loose plasma coil, preventing the station from beaming off wounded passengers. ()

The same year, the  encountered a D12 class Klingon Bird-of-Prey, which had been retired due to its defective plasma coils. The Enterprise then created a low-level ionic pulse to reset the coil and trigger the cloaking device. ()

In 2372, Bejal Otner reported that the plasma coil interlocks were activated when the  was conducting tests on Dr. Lenara Kahn's theory of artificial wormholes, which the Federation was interested in investigating. ()

Fluctuations in the plasma coils could cause a power surge in the warp core. When this occurred, the ship was typically required to take the core offline. ()

See also
Driver coil
Primary drive coil
Resonator coil
Transwarp coil 
Warp coil
Primary warp coil
Teraphasic coil

de:Plasmaspule
fr:Bobine plasmique
Propulsion technology
Warp