Matter-Antimatter (M-AM) Fusion Engine

Much, if not all, of the information written in this article is sourced from Atomic Rockets’ article(s) on [[AM Plasma Core Engines|AM Plasma Core Engines]] and [[AM Plasma Core Engines|AM Plasma Core Engines]]. Any physics equations or mathematics present are copied into this article in their entirety to support the claims made by the Dominionstall setting.—RecolitusMorbus

**Matter-Antimatter** (**M-AM**) **Fusion Engines**, primarily **Antimatter Plasma Core Engines** and secondarily , are capable of intense and tremendous thrust through matter-antimatter annihilation and the direction of plasma heat thrust through magnetic containment. Acceleration is handled well by human bodies through gradually introduced loads and steadily experienced forces, especially by voidborn.

## Plasma Core Engine

Matter-antimatter fusion engines are largely **plasma core antimatter engines**, the core in question a hydrogen-gas plasma ball that is bombarded with a pulsed anti-hydrogen beam, which must be contained in a magnetic bottle utilizing a mirror-solenoid-mirror magnetic containment assembly. The consequence is the plasma ball melting the engine and the propulsion system around it. Exhaust must also be contained via magnetic nozzle, lest the director melt from that as well.

Liquid hydrogen is chosen over water for an incredibly high exhaust velocity traded for nominally reduced thrust.

*Data and specs were taken from Atomic Rockets' article on AM Plasma Core Engines.*

While both water and hydrogen plasma possess the same engine configurations, hyrdogen's incredible potential exhaust velocity when compared to water is only bolstered by hydrogen's tremendous potential specific impulse (*I*sp) despite the a lower compared achievable potential thrust. However, the amount of potential thrust of hydrogen is more than merely 'sufficient' to achieve speeds required to travel star systems.

Hydrogen propellant is injected radially across magnetic field lines while anti-hydrogen fuel is injected axially along magnetic field lines. Upon contact, a hydrogen-antihydrogen annihilation event occurs, the explosion igniting the propellant into plasma. The magnetic containment assembly within the annihilation chamber contains the explosion and directs it into a magnetic nozzle by relaxing the magnetic mirror preventing its ejection. The magnetic nozzle then directs the propellant plasma exit the magnetic bottle. This cycle is repeated for each pulse, the amount of antihydrogen fuel injected matching the hydrogen propellant nuclei for nuclei for precisely controlled ignitions.

The annihilation chamber, a "magnetic bottle," contains the antiprotons, particles charged from the matter-antimatter reaction, and the ionized hydrogen propellant. To keep the engine from being destroyed, the annihilation chamber is installed within the superstructure by a solenoid magnet, capped at the open ends by magnetic mirrors.

Through the magnetic mirrors, the engine is capable of being adjusted to achieve any desired exhaust velocity/thrust combination within its operational range by controlling the amount of propellant and the length of the antiproton pulse. Without the magnetic assembly, the engine would be evaporated in its entirety along with everything else around it.

# F

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{\displaystyle F = \left ( \frac{F\_{normalized} \times 2}{\Delta T} \right ) \times B\_{vol}}

Where

* *F* is thrust in newtons (N)
* *F*normalized is normalized thrust in

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{\displaystyle \left ( \frac{N \times s}{cm^3} \right )}
* Δ*T* is pulse rate in seconds (*s*)
* *B*vol is volume of the magnetic bottle as *cm3*

The propellant mass flow is:

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{\displaystyle mDot\_p = \left ( \frac{m\_p \times n\_p \times B\_{vol}}{\Delta T} \right )}

where

* *mDot*p is hydrogen propellant mass flow in kilograms (*kg*)
* *m*p is atomic mass of hydrogen in kilograms (*kg*) = 1.672621777×10−27
* *n*p is hydrogen density in

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{\displaystyle \left ( \frac{atom}{cm^3} \right )}
* *B*vol = volume of magnetic bottle (*cm3*)
* Δ*T* is pulse rate in seconds (*s*)

The antimatter mass flow is, conveniently:

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{\displaystyle mDot\_{ap} = \left ( \frac{m\_{ap} \times n\_{ap} \times B\_{vol}}{\Delta T} \right )}

Where

* *mDot*ap is antihydrogen fuel mass flow in kilograms (*kg*)
* *m*ap is atomic mass of antihydrogen in kilograms (*kg*) = 1.672621777×10−27
* *n*ap is antihydrogen density in

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{\displaystyle \left ( \frac{antiproton}{cm^3} \right )}
* *B*vol is the volume of magnetic bottle (*cm3*)
* Δ*T* is pulse rate in seconds (*s*)

Optimum performance for plasma core engines utilizes a hydrogen propellant density of 1016 hydrogen atoms per cubic centimeters (*cm3*), and an antiproton density 1010 and 1012 antiprotons per cubic centimeter. Reaction chambers rated for a median reaction time for 5 milliseconds (0,005 *s*) at these densities produce a normalized thrust of 7,6x10-7 N⋅s/cm3 to 9,8x10-6 N⋅s/cm3 with a range of exhaust velocities of 45.000 to 590.000 m/s. The propellant is only captures approximately 11% of exhaust heat while maintaining acceptable levels of bremsstrahlung x-rays.

Thrust can be increased by adding more hydrogen propellant density to 1018 cm-3, but increasing the density from this level, engines experience radiative hydrogen plasma cooling. Such cooling results in a loss of thrust energy. Plasma ejection cannot exceed 200 μseconds (0.0002 *s*) after antiproton injection. Maintaining operation within this restriction will produce a normalized thrust of 8.1×10-5 N⋅s/cm3 with an exhaust velocity of ~49,000 m/s.

Although performance is extremely high (*Isp* ~ 104–105 sec), the long mean free path results in low energy utilization (*ηe* ~ 38%; latest model ability notated circ. 10.322). Other issues include:

* Antiproton (antihydrogen) fuel on the ground restricts acquisition; astronomical delivery fees
* Antiproton containment during transfer between magnetic tanks; high accidental annihilation risk
* Designing an even more efficient switching system for efficient pulsed coil operation
* Longer-lasting antiproton pulse-injection system without significant failure risk
* Longer-lasting radiation shielding for magnetic coils and the crew/passenger habitation areas rated for gamma radiation
* Bem'straalun radiation forcing operating engines to require more antiproton fuel to ignite hydrogen propellant

## Pinch-Fusion Engine

An alternative method of M-AM fusion is the **Flow-Stabilized Z-Pinch Fusion Engine**, also known as the **Z-Pinch** or **Pinch-Fusion Engine**.

## Fuel

Primary fuels used are cryogenically-cooled helium-3 (He3) and deuterium (D). One atom of D is fused with one atom of He3 to produce 18.35 MeV of energy. Only one 0.00285 grams of He3-D fuel must be burned per second to produce one gigawatt of power.

## Radiative Flux Density & RFD Thresholds

**Radiative flux density** is the amount of power radiated through a given area, and in the case of matter-antimatter fusion engines, in the form of gamma and x-ray radiation measured in W/m2.

As matter-antimatter plasma thrust exhaust emits high amounts of ionizing radiation, engines are only permitted beyond a certain threshold of nearby population centers whether it be stations, krysrealms, centaur colonies, or even planets. There is a universal threshold for vessels as well, so that the radiation from either ships’ engines kills the other crew. Vessels on approach to inhabited littoral regions must direct their thrust away from these vulnerable zones as not to accidentally wash them in deadly gamma radiation. For departing vessels the same principle applies, but must adhere to a **radiative flux density** (**RFD**) thresholdlaws and restrictions for the same safety concerns.

In addition to the general distance limitations, common international caeletime laws demand that ships adhere to their RFD threshold, resulting in a thrust maximum based on the distance a vessel has to their destination or other installations. This threshold was devised in response to the amount of potential ionizing radiation produced by voidcraft engines. Larger ships are usually required to accelerate slower and further from littoral zones as well as other manned vessels. These safety precautions have lent to a wide surge of small craft including in-system small voidcraft, systerners, and other like-ships for their inherent speed and nimbleness, but most importantly a less restrictive RFD threshold.

## Known Models

* Rennud Technologies HeH-5-553 Antimatter Plasma-Core Engine