Nuclear electric rocket
In a nuclear electric rocket, nuclear thermal energy is changed into electrical energy that is used to power one of the electrical propulsion technologies. a pebble bed reactor using a high mass-flow nitrogen coolant near normal atmospheric pressures is the most common practice. highly developed conventional gas turbine technologies are leveraged by this. highly enriched, and encapsulated in low-boron graphite balls probably 5-10 cm in diameter is the fuel for this reactor. As the reactor heats, the graphite expands, separating the fuel and reducing the reactor's criticality. This property can simplify the operating controls to a single valve throttling the turbine. When closed, the reactor heats, but produces less power. When open, the reactor cools, but becomes more critical and produces more power and also simplifies refueling and waste handling.Graphite is mechanically strong, and resists high temperatures which reduces the risk of an unplanned release of radioactives. As this style of reactor produces high power without heavy castings to contain high pressures, it is well suited to spacecraft.in nuclear thermal propulsion, the ejected mass was pumped right through the reactor thus getting heated and ejected. in order to keep the thing light we need high temperature, densely packed systems such as fast metal cooled reactors or hexagonal pin fueled, high temperature gas cooled reactors. using the nuclear reactor to drive a turbine to produce electricity was a point of research .
Electrothermal Rocket Engines:
This class of electric rocket engine works by heating a propellant.
1)Resistojets:
A resistojet simply uses electricity passing through a resistive conductor, something like the wires in your toaster, to heat a gas as it passes over the conductor. As the conductor heats up the gas is heated, expands, exits through a nozzle and creates thrust.
2)
Arcjets:
An arcjet is simply a resistojet where instead of passing the gas through a heating coil it's passed through an electric arc.
3)Electrodeless Electrothermal Engines:
There are several variants of the resistojet or arcjet engine that use microwaves or some sort of inductive coupling to heat the propellant. They have some advantage in that power can be coupled directly to the propellant without having to heat part of the engine.
Electrostatic Rocket Engines:
Ion engines:
A electrostatic field can be used to produce thrust in a rocket engine called an ion thruster.As propellant enters the ionization chamber (the small ns on the left), electrons (small -s in the middle) emitted from the central hot cathode and attracted to the outer anode collide with them knocking an electron off and causing the atoms of the propellant to become ionized . the strong electric field of the "+" side repels them and the "-" side attracts them, accelerating them to very high velocities.
colloid thruster
colloids, can be accelerated in a thruster similar to an ion thruster. The advantage of a colloid thruster is that because the individual particles being accelerated are so much larger and heavier than the atoms in a regular ion engine, the specific impulse can be lowered and thrust increased to make a better fit for a particular mission.
Electromagnetic Rocket Engines:
This is by far the largest group of electric thrusters with many different techniques used to create thrust.
1)Rail guns:
Drive enough current down one side of two parallel conducting rails, across a conductor that can slide down the rails while maintaining contact, and up the other side and you have a rail gun.
2)
Hall Thrusters:
These engines are popular with the Russians and over 100 have been used on their space missions.
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