A machine that converts heat into sound energy and then into electrical energy without the use of mechanical parts: Martin was devising an acoustic heat engine which he believed would bring much less expensive electricity to many people in his city.

An expression for early steam engine designs: The term atmospheric engine was given this name because the pressure of the steam was the same as, or near, the envelop of gasses surrounding the Earth.

When Irene was in England, she visited the transportation museum and was impressed with the large atmospheric steam engines on display.

1. An engine operated by the energy released from a combustible fuel that is fed to the engine.
2. An engine that operates by the energy of combustion of a fuel.
3. Any of various types of engines driven by energy produced by combustion.

In spark ignition engines, the sound and other effects associated with ignition and rapid combustion of the last part of the charge to burn, before the flame front reaches it.

A steam engine in which the steam exhaust liquefies in the vacuum space following discharge from the engine cylinder.

1. In rocketry, a reaction engine in which the propellant is accelerated by an electrical device.
2. A rocket engine in which the propellant is accelerated by some electric device.

1. A rocket that is accelerated by means of a plasma engine or an electrical-reaction engine in which magnetically accelerated plasma is used as the propellant.
2. An engine for space travel in which neutral plasma is accelerated and directed by external magnetic fields that interact with the magnetic field produced by electric current flow through the plasma.

The term plasma in these definitions refers to a gas-like state of matter consisting of positively charged ions, free electrons, and neutral particles.

Plasma is found in the stars, the sun, the solar wind, in lightning, and in fire.

1. The engine management system that controls the ignition system and various other systems, including the exhaust gas recirculation and air-injection systems.
2. A precision control of engine-spark timing and exhaust gas recirculation for emissions control and fuel efficiency.

1. A flight vehicle engine utilizing spark discharges through which intense electric and magnetic fields are established, for periods ranging from microseconds to a few milliseconds, generating an electromagnetic force which drives plasma along the leads and away from the spark gap.
2. An engine set up for propelling a flight vehicle which is based on the use of spark discharges through which intense electric and magnetic fields are established for times ranging from microseconds to a few milliseconds.

A resulting electromagnetic force drives the plasma along the leads and away from the spark gap.

1. A rocket engine that develops thrust by expelling ions rather than gaseous combustion products.
2. An engine that provides thrust by expelling accelerated or high-velocity ions.

Ion engines using energy provided by nuclear reactors are proposed for space vehicles.

3. A type of rocket engine that generates thrust from the electrostatic acceleration of ionized particles.

A motor designed for use in propelling a water vessel: A marine engine is one that is enclosed within the hull of a craft, as opposed to an outboard motor which is mounted outside the hull of boat.

Another term for a piston engine: A reciprocating engine is one that employs one or more pistons to convert pressure into a rotating motion.

A general term for any power source that is driven by solar energy; such as, a system of solar panels used to power an electric propulsion system.