Arcjets are a form of electric propulsion, whereby an electrical
discharge (arc) is created in a flow of propellant (typically
hydrazine
or
ammonia). This imparts additional energy to the propellant, so that
one can extract more work out of each kilogram of propellant, at the
expense of increased power consumption and (usually) higher cost. Also,
the
thrust levels available from typically used arcjet engines are very
low compared with chemical engines.
See also: spacecraft propulsion