As everyone knows, warp drives operate by [...brief summary... By maintaining a continuous reaction, a small volume around the ship is enveloped in a warp field, displaced from normal space. If the antimatter reaction stops, the field will collapse within 4 seconds.]
But in more detail...
On the large scale, however, subspace is strictly bound by galactic structure. It forms energy barriers in bands around the center of the galaxy, cutting off our region of space from the galactic rim and from the galactic center.
Further, local subspace is polarized into `sheets' of interaction parallel to the plane of the galactic disk. This makes warp travel along the galactic plane over 8 times easier than warp travel perpendicular to the plane, and it applies similarly for other subspace phenomena.
This displacement is described as a subspace field, which can be represented by picturing space as a flat, two-dimensional plane - where the subspace field is a small bump on that surface. Unless the displacement is carefully maintained, however, the field will disperse outwards as subspace waves.
Subspace waves pass through normal matter, occaisionally interacting with the matter in a regular pattern defined by the frequency of the wave. Most waves are unmodulated and will propagate in all directions like sound waves, with only very weak interaction with matter. However, in controlled conditions, subspace waves can be phased to form directional rays which interact more strongly with matter, resonating with different levels of electromagnetic structure.
To the outside universe, matter within the central region of a warp field appears to have a lower effective mass than usual. Further, energy which passes into the warp field through the interaction region will be distorted or reflected.
The starship can be propelled faster than light by creating a nested series of asymetrical warp fields. Inside the warp nacelles, a reacting stream of matter and antimatter is maintained in a continuous, shaped path to create the fields. The warp field then propel the ship by transfering momentum into subspace, increasing with each nested field.
Maneuvering is accomplished by a more intense matter-antimatter reaction at the central intermix chamber. The resulting subspace reaction is then focussed by (traditionally) dilithium crystals, affording greater control over the resulting field shape. This is used to accelerate, decelerate, turn, and modulate the standing warp fields projected from the nacelles.
Thus, under normal operation, the warp drives are continuously active (at a low-level), to power the magnetic containment. It is possible to shut down warp engines so that there is no warp signal from them. However, the process is time-consuming and dangerous. It takes approximately a half hour to safely shut down the engines, and about 15 minutes to restart them. If power flow to the nacelles is cut off during the shutdown, the antimatter will instantly explode.
The dilithium crystals inherently focus subspace energies due to their unique nuclear resonance. The position of the crystals is minutely altered by engineering controls to control various warp functions of the ship. However, an overload of subspace energy can cracks the dilithium crystals. Cracked crystals cannot generally be repaired - they must be replaced, and due to limited supply, no spares are carried. If too much antimatter is annihilated, the signal may crack many or all of the crystals. While it is recognized that pushing the engines may be neccessary, conservative procedure is urged.
The power producing capacity of a warp drive is enormous. In metric terms, a point of power output is approximately 800 million watts of usable power to dilithium-based functions, with about 12% of that usable through the ships superconducting power lines. Direct warp functions, such as deflector shields and photon torpedoes, have significantly more power available.