Many ships with fusion drives have supplemental ion drives that use electricity generated from the fusion reactor as an energy source. These ion engines supplement the thrust of the ship at little additional cost of mass. Some smaller ships - especially modern tenders and shuttles that are not intended for interstellar flight - often have a small fusion reactor solely as a power source and derive all of their thrust from ion drives. While the ion drive does not operate within an atmosphere, it can be a useful propulsion method during space-born portions of space-to-surface operations. Tghis saves fuel for conventional plasma or chemical thrusters to be used during atmospheric operations.
In an ion drive, an inert gas is introduced to a reaction chamber. Electricity is introduced to the gas, knocking electrons from the atoms and rendering an ionized version of the gas. The process of exciting the subatomic particles also heats the reaction chamber, resulting in the ionized gas becoming a super-heated plasma. The resulting reaction builds pressure that is ejected through a thrust nozzle utilizing a polarized magnetic field, generating a high ration of thrust with a relatively low amounts of fuel and energy requirements.
In addition to generating the primary thrust of a ship, the fusion reactors on board a spacecraft also generate all of the power required to operate the ship's systems. Electricity for computers, life support, lighting, and other applications all come from the fusion reactors. As mentioned before, some of this power might even be diverted to ion drives for additional acceleration thrust or maneuvering thrusters.
An engine room with two fusion drives.
One of the major advantages of the constant, sustainable reaction in a fusion reactor is providing a steady supply of energy for recharging the capacitors for the ship's Singularity Drives
. These systems require an enormous amount of power, and even a ship equipped with multiple fusion reactors must spend time recharging the capacitors to store enough energy to initiate a Faster Than Light Travel