Fusion Power

Fusion Power is the primary source of power throughout the solar system, with a few limited uses of fission and electrochemical energy. Fusion is used to both propel ships through induced fusion drive, and to power stations or ships through torus rings.

Induced Fusion Drive
Induced Fusion Drive (also known as a "fusion rocket") was the first commercial use of fusion, predating fusion as a power source by almost three decades. IF Drives were the first engines efficient and powerful enough for interplanetary exploration, but colonization wasn't possible until the advent of the Particle Drive.

Induced Fusion uses an array of neutron spallers to direct beams of neutrons into a specific point in a cloud of gas. The concentration of the neutrons causes fusion without the need for as extreme temperatures as fusion naturally occurs at. As that very few atoms involved in the reaction actually "fuse," this reaction is relatively inefficient.

The biggest advantage of the IF Drive is that ithe reaction is entirely external and--ignoring the neutron spallers--the reaction is largely self-powering. IF Drives do not require powerful reactors or Carnot ports, so moving within a planet's gravity-well is often done with an IF Drive.

Trivia: With the exception of a few museum pieces, the first generation IF Drives used to power manned explorations were updated and recycled as the first stages for interstellar probes.

Torus Fusion Reactors
Torus fusion reactors--paired with a Carnot port--is how most energy is produced for most applications, from small transports to space colonies, although some holdovers of fission reactors exist. Fusion as a power source is a relatively new technology, as that control and confinement required more energy than the reactor produced. Finally, using permanent superconducting magnets to supplement a confinement field, the design finally broke even in the mid-twenty first century, but even then it wasn't a practical power supply.

Unlike fission reactors, efficiency is of little concern for a fusion reactor. Fissile fuels such as Uranium and Thorium are relatively rare and difficult to refine, while Hydrogen is the most common element in the universe. As that all reactors are limited in their output by the Carnot ports they are paired with, simply upgrading the reactor does not translate to a larger energy output--in fact, quite the opposite; fusion reactors leech off some of the energy they produce for confinement, and are larger and heavier than fission reactors. The only factor which changes is the expense of the fuel, which almost always justifies the exchange.

Fusion technology is also constantly developing. The mass of the Hydrogen fuel--and particularly the needed containers to hold it--is a significant drag on accelerating space transports, so slight differences in efficiency translate to significant overall savings. Transport companies usually sell off their old fleets to consumer markets to finance purchasing newer fleets.

Torus Fusion reactors also take advantage of neutron spalling, using it to "cheat" the break-even equations of continuous hot fusion. Rather than compressing Hydrogen until it fuses, a relatively cold Hydrogen gas is "flashed" with neutrons to momentarily induce fusion. The Hydrogen releases the heat produced by the fusion, cools back down, and is flashed again.