What are the current types of thrust propulsion, how strong is each type of thrust, and in what conditions?

Question

would such thrust be useful? Solid Rocket, Liquid Rocket, Hybrid Fuel rocket, Hall thruster, Electrical thrust, Ion Thrust, Photon Thrust, Magnetic Thrust, Ramrocket, Air breathing rocket, Space breathing rocket, etc etc? How do these work? what else is there?
which are the most useful?
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Answer 1

First of all, it depends on what you need the thruster for. Chemical rockets (solid, liquid, and hybrid) are the only ones with strong enough thrust to get off the Earth, but once you're in orbit even a low continuous thrust will get you where you want to go, if you have the time.

Chemical rockets combine fuel and oxidizer to create thrust. Liquid and solid fueled rockets are just what they sound like; hybrids use a solid fuel but a liquid oxidizer to to start and stop the burn. This helps to deal with one of the biggest problems with solid fuel rockets - once they're lit, they can't be shut off. A hybrid can be throttled off just by stopping the flow of oxidizer.

Hall effect and ion thrusters are a bit different. They use a fuel (typically a light gas, but there's a particular type that uses solid Teflon) that is ionized and then passed through a magnetic field to accelerate it to very high speeds. The drawback is that the acceleration is very low, so it can't be used to launch off the Earth. The plus is that you don't really need the high thrust of a chemical rocket in space - it just takes you longer to get anywhere. There was a British spacecraft that went from Earth orbit to the Moon using only ion thrusters; it took eighteen months!