The Complete Book of Spaceflight: From Apollo 1 to Zero Gravity

120 electrostatic propulsion
electrothermal propulsion
electric propulsion electrostatic propulsion
electromagnetic propulsion
electric propulsion The various types of electric propulsion.
and popular is the heavy inert gas xenon, which is used in
the XIPS (xenon-ion propulsion system). The gas propellant
enters a discharge chamber at a controlled rate. A hot
cathode (negative electrode) at the center of the chamber
emits electrons, which are attracted to a cylindrical anode
(positive electrode) around the walls of the chamber.
Some of the electrons collide with and ionize atoms of
the propellant, creating positively-charged ions. These
ions are then drawn toward a high-voltage electric field
set up between two closely spaced grids at the downstream
end of the chamber. These grids contain numerous
tiny lined-up holes so that they serve as porous
electrodes. The ions are drawn through the first grid (the
screen grid), are accelerated in the narrow gap between
the first and second grid (the accelerator grid), and then
pass through the second grid as a fast-moving ion beam.
On the downstream side of the accelerator grid, electrons
are injected back into the beam before it is expelled so
that the spacecraft remains electrically neutral. If only
positively-charged ions were allowed to escape, the vehicle
would become more and more negatively-charged
until it prevented the thruster working at all.
ion propulsion
arcjet thrusters
resistojet thrusters
microwave plasma thrusters
electron bombardment thrusters
contact ion thrusters
field emission/colloid thrusters
Hall-effect thrusters
pulsed-plasma thrusters
magnetoplasmadynamic thrusters
helicon thrusters
electrostatic propulsion
A form of electric propulsion in which the thrust is produced
by accelerating charged particles in an electrostatic
field. It includes three types of device: electron bombardment
thrusters, ion contact thrusters, and field
emission/colloid thrusters. Of these, the first two
involve the production and acceleration of separate ions
and are therefore forms of ion propulsion. The third
type involves the production and acceleration of charged
liquid droplets. Only electron bombardment thrusters
have been used operationally aboard spacecraft.
electrothermal propulsion
A form of electric propulsion in which electrical energy
is used to heat a suitable propellant, causing it to expand
through a supersonic nozzle and generate thrust. Two
basic types of electrothermal thruster are in use today:
the resistojet and the arcjet. In both, material characteristics
limit the effective exhaust velocity to values similar
to those of chemical rockets. A third, experimental type is
the microwave plasma thruster, which potentially could
achieve somewhat higher exhaust velocities.