Plasma from the warp core is transferred through a craft's warp nacelles via plasma injectors. Inside the nacelles are split toroids consisting of multiple layers of various materials, the intricacy of which precludes replication so far. The coils are composed of verterium cortenide, which is a densified composite material composed of polysilicate verterium and monocrystal cortenum.
When plasma passes through the warp coil assembly, the coils generate a multi-layered set of fields around the craft that, when operated properly, create the propulsive forces enabling FTL speeds to be achieved. The fields themselves are actually the results of the distortions created by the craft's subspace generators - the coils - and subspace. Manipulation of the configuration of the fields determines the craft's velocity and direction.