Resonator coil

A resonator coil is a component of a warp core.

In 2368, a Romulan science vessel suffered a forced chamber explosion in their resonator coil as a result of attempting to utilize an experimental interphase generator. This had the effect of completely depolarizing the coil's graviton field generator, rendering it useless. 

After being trapped inside a subspace pocket by a subspace sinkhole in 2375, Tuvok, Tom Paris, and Noss salvaged a pair of resonator coils from one of the ships crashed on their planet. On the way back to their shelter, they were attacked by scavengers and the coils were stolen.