Sublight Drives

Plasma Rockets: 

A truism of rocket science and engine design states that the hotter the exhaust of a rocket, the more thrust it will generate per unit of fuel. Plasma rockets heat their fuel to the plasma state, stripping the atoms of their electrons in the process. The extreme heat and pressure requirements mandated for plasma ignition precludes standard materials from usage as containment vessels or exhaust nozzles. Since plasmas are electrically active however they can be contained within powerful electrostatic and electromagnetic fields. Fields of sufficient strength can likewise be shaped and directed to provide either containment or thrust. Plasma rockets are related to the larger, more powerful, fusion rockets as many designs utilize the plasma generated by a fusion reaction as their reaction mass. Most plasma rockets do not utilize direct plasma flow from a fusion reactor however due to the dangers inherent in the then radioactive exhaust. Non-fusion plasma rockets also feature lower mass as they do not require the same level of radiation shielding to protect the spacecraft and its crew. The lack of radioactive exhaust makes plasma rockets ideal for use by transatmospheric craft or in large scale probes and weapon systems. Specific Impulses are measured in excess of 347,000 centipulses (100,000 seconds). 

 Electron Beam Plasma (EBP) Engine: 

The most common Plasma Engine design at the time of UCSB-GF war, the Electron Beam Plasma
(EBP) engine injects a relativistic electron beam into a compressed reactive fluid, in most cases hydrogen, superheating it to the plasma state. Powerful magnetic mirror fields contain the resultant explosive reaction and direct the plasma out of the rocket nozzle generating thrust. These engines feature dynamic controlled thrust systems where the magnetic fields and/or catalyzing electron beam, depending on manufacturer and model, are adjusted. EBP Engines often make up the core of the Electron Beam Fusion Engines, however the EBP does not produce the radiation of its more energetic fusion version. EBPs also require an external power source.

Fusion Bulb Plasma (FBP) Engine: 

Fusion Bulb Plasma (FBP) Engines function in much the same fashion as EBPs but integrate a fusion powerplant. The waste heat from the fusion plant is then utilized to superheat the reaction mass to the plasma state. Most also include throats that allow for direct venting of plasma generated within the fusion plants as well, with a corresponding increase in radioactive output. Since these engines include their own power source they are often favored use in simpler spacecraft and single usage engines like those on probes and torpedoes. 

Combined Cycle Plasma (CCP) Engine: 

The Combined Cycle Plasma Engine is the standard drive used by the majority of fighter spacecraft and is the combination of an EBP or FBP with an additional Plasma Fuser stage. In normal function the engine operates exactly like the standard EBP/FBP making it usable in biospheres with minimal impact. The fuser stage contains an extremely powerful dynamic control magnetic field generator that when activated drastically increases the electromagnetic pressure on the plasma flow until it reaches the fusion point. These so-called Fusion Torches, or simply Torches are used for short bursts of high acceleration and are especially useful in combat craft where such large accelerations are required to counter the momentum vector of combat maneuvers. Use of Fusion Torches is limited within atmosphere where Plasma overdrives are engaged instead unless operational overrides are implemented.

Fusion Drives:

 Fusion is the process by which atomic nuclei are fused together to form heavier chemical elements. In most cases hydrogen, or associated isotopes, are fused together to create helium. The resulting reaction converts measurable quantities of the original hydrogen atom’s mass into usable energy. The energy manifests in the form of super hot, high velocity plasma, which in the case of fusion drives is expelled for thrust. Fusion rockets are attractive as spacecraft propulsion as they have been measured to have specific impulses in excess of 1,041,000 centipulses, 300,000 seconds. 

 Deuterium-Tritium Fusion (DTF): 

 The type of fusion reaction first achieved by most races if of course the type considered to the be easiest to obtain, Deuterium-Tritium Fusion (DTF). This reaction however unfortunately produces high-speed neutrons as a byproduct. All neutrons are electrically neutral and as a result, magnetic field traps do not readily contain those neutrons created by DTF. This creates a problematic radiation hazard, one that mandates the use of heavy physical shielding instead of mirror fields or magnetic traps. Physical shielding cannot be used indefinitely however and will become saturated with radiation over time requiring its decontamination and or eventual disposal. As a result DTF reactors and engines have to be regularly refitted with new shielding after reaching saturation point. 

Deuterium-Helium-3 Fusion (DH3F): 

The next step in fusion power plants and engines comes from the fusion of Deuterium and Helium-3. DH3F has a greater energy/thrust yield then DTF for relatively little more complexity, and has the added benefit of not producing neutronic radiation as a by-product. Helium-3 however is not a readily available fuel source to be found floating in space or any known terrestrial world, found primarily in the crusts of dead moons and in the atmosphere of gas giants. 

Deuterium-Deuterium Fusion (DDF): 

The next step in the fusion chain is somewhat harder to obtain. DDF reactions require temperaturesand pressures an order of magnitude greater then DTF or DH3F. The benefit however comes in the increasingly higher energy release. DDF reactors/engines are also more attractive due to the fact that deuterium is much easier to obtain then Tritium, which is produced from Deuterium, or Helium-3, naturally occurring in many oceans, and is relatively easy to produce artificially.

Hydrogen-Hydrogen Fusion (HHF): 

Also known as proton-chain fusion, Hydrogen-Hydrogen Fusion utilizes the most abundant atom in the cosmos, Hydrogen, as its fuel source. The required temperatures and pressures to create such a reaction however are several orders of magnitude higher then even DDF reaction and are best observed in the heart of stars. Such reactions are therefore reserved only for power generation on planet, onboard space stations, and in very rare cases aboard supermassive capital ships. 

Fusion of heavy elements is possible, seen most often in the heart of supermassive stars and in those stars leaving the main sequence. This method of fusion however is not addressed as a practical means of power or propulsion, limited only to those refusion reactors that split or recombine atomic elements which have been used in fusion or fission powerplants.

In almost all cases the containment and direction of fusion reactions and the resulting plasma in a spacecraft engine is done via the use of powerful magnetic fields, better known as Magnetic “Bottles” or Mirror Fields. A magnetic bottle is the superposition of two magnetic mirrors. For example, two parallel coils separated by a small distance, carrying the same current in the same direction will produce a magnetic bottle between them. Particles near either end of the bottle experience a magnetic force towards the center of the region; particles with appropriate speeds spiral from one end of the region to the other and back. Magnetic bottles are therefore used to trap the charged particles and plasmas created during the fusion reaction.

Fusion rockets/reactors have their drawbacks however, the most critical of which is the radiation that all of them produce during the fusion reaction, in addition to the neutrons of DTF reactors. This mandates the use of a shielding system to protect the crew, which comes in the form of either heavy physical shields, or energetic mirror fields. The plasma exhaust that results from the fusion reaction also proves radioactive, and has resulted in laws that levy strict controls over the use of fusion drives on and around inhabited worlds.

Numerous types of Fusion Engines are in use throughout the galaxy, but the most common types are listed here:

Deep Plasma Focus Fusion Drive (DPFFD): 

Better known as the Spike Drive, a Deep Plasma Focus Fusion Drive (DPFFD) is a relatively simplein concept but requires very powerful magnetic fields that limit their use. In a Spike Drive, plasma from the main reactor is forced down a long, cone-like magnetic “funnel” that continually compresses the plasma until reaching the cone’s apex. At this point, the pressure generated by the magnetic field exceeds the plasma’s particle pressure, resulting in a fusion reaction. This system is not the most ideal however because it is basically on or off, with minimal throttling capacity since the plasma flow forced down the magnetic funnel at such high pressures keeps the entire system firing continuously. As with most Fusion drives, this engine can be scaled back into a plasma rocket by adjusting the magnetic field strength and the throat of the fusion apex.

Combined Cycle Plasma/Fusion Engine: 

The Combined Cycle Plasma/Fusion Engine is the standard drive used by the majority of lightspacecraft and is, in essence, a combination of the DPFFD and an EBF or FBP Engine. These engines feature a dynamic controlled thrust system where the magnetic fields and/or catalyzing electron beam, depending on manufacturer and model, are adjustable so the same engine can function as both a plasma and a fusion rocket of varying outputs. This has proven advantageous in craft designed to operate both within a planet’s atmosphere as well as in deep space, such as dropships, and corvettes. When near a planet or in atmosphere the engine acts as a plasma rocket cutting the radioactive emissions of it exhaust to safe levels that do not endanger local biospheres. When a safe distance from the planet has been reached however, the engine transfers into fusion mode, giving greater thrust and fuel efficiency and allows of more rapid deep space travel.

Pulse Drives: 

Pulse drive is the generic blanket term used to describe any large scale drive system that uses pulse detonation to generate thrust. Early pulse drives used nuclear pulse detonation while the most advanced in use anti-matter as the pulse fuel source. Like fusion drives pulse drives have their drawbacks however, the most critical of which is the radiation that all of them produce during the pulse detonation. This mandates the use of a shielding system to protect the crew, which comes in the form of either heavy physical shields, or energetic mirror fields. The exhaust that results from the pulse detonation also proves radioactive. This has resulted in laws that strictly control the use of pulse drives on and around inhabited worlds. Due to the variety of races present in the galaxy at various technology levels all manner of pulse drives can be discussed but only the three most common type will be discussed here: 

Reaction Pulse Detonation (RPD) Drive: 

Reaction Pulse Detonation Drives were for many races the first practical means by which theyreached out to the outer planets of their solar systems and to the star beyond. At its most basic the RPD works by detonation of a reaction warhead behind a pusher plate which in turn propels the craft. In general, the drive works by ejecting a specialized reaction warhead a few hundred metra behind the ship. These warheads are usually coated with some form of polyethylene plastic, that upon detonation expand into massive plasma clouds that strike the pusher plate to generate force.

Further the plastic acts as a first stage radiation shield absorbing stray neutrons from the explosion, protecting the crew, and breaks down into light-weight hydrogen and carbons atoms which travel at tremendous speed when agitated. In order to limit the otherwise crushing acceleration forces on the rest of the ship generated by such an explosion, the pusher plates are invariably separated from the rest of the ship by gigantic shock absorbers.

Thanks in part to the open pusher-plate design and lack of combustion chamber, RPD drives have very high upper limits on the amount of heat and thrust generated that they can withstand. With specific impulses that can vary from 35,000 to 3,500,000 centipulses, 10,000 to 1,000,000 seconds, these drives are quite attractive to more primitive civilizations.

Fusion Pulse (FP) Drive: 

Fusion Pulse Drives operated under the same general principal of the RPD but instead of launchinga reaction warhead into the wake of the craft they set off a fusion reaction within an open reaction chamber. Also known as Internal Confinement Fusion, most Fusion Pulse Drives use lasers and or particle beams to detonate packets of fusion fuel, typically Deuterium, Tritium or Helium-3. The resultant explosion of the fusible fuel generates a plasma wake that in turn pushes against the walls of the reaction chamber, propelling the ship.

These tend to be more attractive than RPDs and, via the use of magnetic controls, have their own built in first level radiation shield. Additionally, the increased specific impulses, which have an upper limits on the order of 35,000,000 centipulses (10,000,000 seconds), make them nearly as attractive as the more advanced Pulse-Photon Drive.

 Photon-Pulse (PP) Drive: 

The photon-pulse drive, generally referred to as a pulse drive, is the backbone of interstellar traveland powers most large scale capital ships, having supplanted most other pulse drive types. Current pulse drives use arrays of advance concave gamma ray mirrors that reflect the intense highly energetic gamma rays created by matter-antimatter annihilation.

These gamma ray mirrors are required to have a reflective bypass ratio of less then 1e-10 of the incoming energy to be certified for safe use and be able to do so without measurable degradation in the reflective surface. The matter-antimatter reaction is precisely targeted to take place in the focal point of the concave mirror, which then acts like a pusher plate similar to nuclear pulse detonation drives. Due to the fact that reaction is placed directly in the mirror’s focal point, all light impinging on surface from the reaction is reflected straight back. This gives the gamma-ray mirror portion of the pulse-photon drive a specific impulse on the order of 69 million centipulses, 20 million seconds, per mirror. Additionally large-scale photon-pulse drives typically feature a beam-core antimatter rocket, which exhausts through a variable choke throat in the apex of the mirror.

The Beam-Core antimatter rocket utilizes a diverging magnetic field precisely located upstream of the annihilation point between the antimatter and low-density hydrogen. The magnetic field then focuses the energetic charged pions as the exhausted propellant. These charge pions are ejected at nearly light speed and add a specific impulse of greater then 35 million centipulses, 10 millions seconds, per nozzle.

The addition of this drive nozzle to the gamma-ray mirror of the pulse-photon drive creates a 40% thrust increase in the anti-matter rocket and gives a combine specific impulse on the order of 117 million centipulses, 34 million seconds, per hybrid cell. 

Gravitational/Reactionless Drives: 

Gravitational or reactionless drives are the technology to which all drives hope to eventually progress. Such drives would require no fuel, only power and would leave no harmful radioactive exhaust. To date only small scale gravitational or reactionless drives have been constructed by the younger races though their practical application is demonstrated regularly by older races like the Donvarion and Pharad. 

Antigravity: 

Anti-Gravity Field (AGF) generators work in much the same way as Graviton Spinners.  The AGF uses a graviton spinner at its core. Instead of emitting directed graviton fields into open space it first passes them through an electrically charged composite dark matter ribbon mesh. The charged mesh enacts an electro-gravitational effect upon the graviton wave that reverses the waveform on the quantum level creating a repulsion force against nearby objects – the practical application of which means that when used inside of a gravitational field an AGF floats because the field of anti-gravitation waves that it creates cancels out the gravitational waves in the gravity field. This repels the object with the lowest gravitational potential away, in this case the AGF equipped vehicle or ship.

AGF Generators require more power to operate than do standard graviton spinners, and do not have the long wind up times of the graviton spinner.

This is for two reasons: first, a graviton spinner used for artificial gravity creation must create a uniform field, whereas the AGF generator can get away with a far less cohesive field, sometimes resulting in “gravity bumps.” Second, a standard Graviton Spinner spins up slowly in order to prolong its useful life. The rapid spin up of an AGF limits that lifespan to a few annura at most of regular use.

AGFs lose their useful potential the further from a strong gravitational source or object they are. This makes them impractical for use as orbital launchers but still gives a launch boost at take off.

Experiments have been conducted on the use of AGFs in space for propulsion and maneuvering. These experiments have met with limited success as AGFs require a larger mass to push off in order create meaningful movement. Research is ongoing however as the presence of gravitational drives by more advanced races shows that gravitational propulsion methods are possible.

Particle Duct Engine (PDE): 

Early particle duct engines did not us gravitational manipulationbut were air-breathing engines that used magnetism to manipulate air in much the same way as a jet engine. Their popularity continued and spread throughout confed space and were further refined.

The specialized magnetic field generators were eventually replaced, tuned to the unique magnetic signature of a planets air, with gravitomagnetic attractors. Arranged in long coiled channels these drives seemed to reach their peek and formed the backbone of nearly all air-breathing engines. It was eventually realized that these gravitomagnetic PDEs could be used in space to limited effect.

Unfortunately, generating significant thrust required running the gravitomagnetic spinner coils to the point of near immediate collapse. It seemed that the technology would therefore before forever relegated to using the engines as powerplants to short lived torpedoes where the threat of imminent coil collapse would not be considered as crippling.

Experimentation on atmospheric PDEs by a professional air racer mechanic led to the breakthrough that allowed true space born PDEs. The combination of a PDE, a graviton spinner and grappler-repulsor beam created the first true gravitic PDE. The integration and combination of these devices allowed the accelerator coils to project a pinpoint field of gravity ahead of the intake. The engine then “falls” into the gravity point source, dragging it forward all the while maintaining its initial distance from the projected point that continues to drag the engine. 

The point source will develop a pseudo-mass however, which upon developing its own momentum and inertia requires more energy to move then it originally provided. To counter this effect a linear series of accelerator coils are employed. The first series of coils project the gravitation point sources that the engine “falls into” while the remaining series of coils pull the pseudo-mass and real mass down the length of the engine before expelling it out the exhaust for added thrust. Once clear of the exhaust any pinpoint gravity sources that are pulled along with the pseudo mass dissipate back into the quantum level before they can generate significant drag on the engine The rapid succession of these pinpoints, on the order several hundred per centipulse, ensure a smooth ride where few crew can experience any change in acceleration.

The pseudo-mass and real mass created/collected by the engine need not all be expelled. In the case of drives used by small craft, like fighters, the collected mass is stored in collection ports and when needed is reintroduced to the engine exhaust stream to add short bursts of acceleration or deceleration. Similarly the intake design allows for an inbuilt reverse thrust system as the engine is basically thrown into reverse, projecting the point source behind or inside the engine, if the gravitational potential is not too great.

As of UCSB annura 1000 these system are still highly experimental are projected to be of a serviceable condition within a decade.

 Gravity Drag Drive (GDD):

The fact that the Particle Duct Engine requires an intake towork makes them impractical to adapt or utilize aboard large scale starships. An engine based on the basic concept, however, is theorized to form the basis of the gravity drives of those craft used by the ancient races. Analysis of debris left by some of these ships has provided some insight, but the external nature of the design makes them vulnerable to attack and analysis difficult.

Theoretically the drives employ a series of gravity vanes or spikes, as is typically observed, which act like an inside out PDE. A GDD should work in much the same way as PDE, the forward most vanes or spikes generate a series of small short lived gravity point sources ahead of the ship’s center or gravity. The vanes/spike in trail then act in much the same way as accelerator coils, pulling the point sources, and any pseudo-mass or real mass they collect down the length of the engine, with the last series pushing them past the craft. In addition, the primary spikes/vanes can create much more intense, and longer lasting point sources further out from the ship for increased acceleration or create a point source behind the ship to slow it.

The system appears to work in pulsed fashion on the order of several thousand cycles per centipulse allowing some ships to even out accelerate their own acceleration limits.

Gravity Wave Pulse Drive: 

A purely theoretical drive at the time of the UCSB-GF conflict many believe this drive or possibly a variant of the GDD is the primary gravitation drive used by the ancient races. The theory states that a high energy fusion reaction, possibly Deuterium-Deuterium, or Hydrogen-Hydrogen is contained and modulated using a combination of an electromagnetic field, gravitic containment field, and possibly a field that can manipulate the strong nuclear force.

It is known that the Donvarions at least have such a field that can manipulate the strong nuclear force on the quantum level, though the method by which this is done is unknown, as only its effect has ever been observed by non-Donvarion. This combination of fields focuses the fusion implosion such that it generates microscopic, short-lived black holes, called “black points”, whose gravity waves are then manipulated to push or pull the ship as desired. It is believed that this drive would constantly generate these black points that fade back into the quantum ether after a few nanopulses, though such a thing has never been proven. If true, though, those few nanopulses in steady succession would be all that the ship required for propulsion.

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