Fusion Pulse Engine

The Fusion Pulse Engine is an old spacecraft propulsion system that uses pulsed inertial confinement fusion reactions for thrust.

Characteristics

For space flight, the main advantage of a fusion engine is the very high specific impulse, and the main disadvantage the large mass of the reactor. However, a fusion rocket may produce less radiation than a fission rocket, reducing the mass needed for shielding.

A fusion drive can have a specific impulse about 300 times greater than conventional chemical rocket engines. Fusion-powered rockets also provide longer thrust than chemical rockets, which burn their fuel quickly.

Additionally, fusion-powered rockets use hydrogen as a propellant, which means spacecraft are able to replenish their fuel stores as they travel through space. Hydrogen is the most abundant element in the Universe and present in the atmosphere of many planets, so all the spacecraft has to do is dip down into the atmosphere and suck in some hydrogen to refuel itself.

Mechanism

The engine uses small pellets of fusion fuel, typically lithium deuteride (6Li2H) with a small deuterium/tritium trigger at the center. The pellets are thrown into a reaction chamber where they are hit on all sides by lasers or another form of beamed energy, such as electron beams. The heat generated by the beams explosively compresses the pellet, to the point where fusion takes place. The result is a hot plasma "exploding" in pulses.

The process is run within a large electromagnet. After the reaction, the magnet funnels the hot gas to the rear for thrust. Some of the energy is diverted to run the ship's systems and engine.