Ion wind
Encyclopedia
Ion wind, ionic wind, or coronal wind is a stream of ionized fluid generated by a strong electric field
. Francis Hauksbee
, curator of instruments for the Royal Society
of London, made the earliest report of electric wind in 1709. Myron Robinson completed an extensive bibliography and literature review during the 1950s resurgence of interest in the phenomena.
Electric charges on conductors reside entirely on their external surface (see Faraday cage
), and tend to concentrate more around sharp points and edges than on flat surfaces. This means that the electric field generated by charges on a sharp conductive point is much stronger than the field generated by the same charge residing on a large smooth spherical conductive shell. When this electric field strength exceeds what is known as the corona discharge
inception voltage (CIV) gradient, it ionizes the air about the tip, and a small faint purple jet of plasma
can be seen in the dark on the conductive tip. Ionization of the nearby air molecules result in generation of ionized
air molecules having the same polarity as that of the charged tip. Subsequently, the tip repels the like-charged ion cloud, and the ion cloud immediately expands due to the repulsion between the ions themselves. This repulsion of ions creates an electric "wind" that emanates from the tip, which is usually accompanied by a hissing noise due to the change in air pressure at the tip.
Unlike the functionality of the Electrohydrodynamic (EHD) thruster
, the net force generated by an ion wind device does not rely on the momentum transfer between the charged and the neutral air molecules, but only on the impulse that the charged ion
s gain during their repulsion from the tip. It is analogous to recoil
of a gun
when it fires a bullet
.
Electric field
In physics, an electric field surrounds electrically charged particles and time-varying magnetic fields. The electric field depicts the force exerted on other electrically charged objects by the electrically charged particle the field is surrounding...
. Francis Hauksbee
Francis Hauksbee
Francis Hauksbee the elder , also known as Francis Hawksbee, was an 18th-century English scientist, and a Fellow of the Royal Society...
, curator of instruments for the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
of London, made the earliest report of electric wind in 1709. Myron Robinson completed an extensive bibliography and literature review during the 1950s resurgence of interest in the phenomena.
Electric charges on conductors reside entirely on their external surface (see Faraday cage
Faraday cage
A Faraday cage or Faraday shield is an enclosure formed by conducting material or by a mesh of such material. Such an enclosure blocks out external static and non-static electric fields...
), and tend to concentrate more around sharp points and edges than on flat surfaces. This means that the electric field generated by charges on a sharp conductive point is much stronger than the field generated by the same charge residing on a large smooth spherical conductive shell. When this electric field strength exceeds what is known as the corona discharge
Corona discharge
In electricity, a corona discharge is an electrical discharge brought on by the ionization of a fluid surrounding a conductor that is electrically energized...
inception voltage (CIV) gradient, it ionizes the air about the tip, and a small faint purple jet of plasma
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...
can be seen in the dark on the conductive tip. Ionization of the nearby air molecules result in generation of ionized
Ionization
Ionization is the process of converting an atom or molecule into an ion by adding or removing charged particles such as electrons or other ions. This is often confused with dissociation. A substance may dissociate without necessarily producing ions. As an example, the molecules of table sugar...
air molecules having the same polarity as that of the charged tip. Subsequently, the tip repels the like-charged ion cloud, and the ion cloud immediately expands due to the repulsion between the ions themselves. This repulsion of ions creates an electric "wind" that emanates from the tip, which is usually accompanied by a hissing noise due to the change in air pressure at the tip.
Unlike the functionality of the Electrohydrodynamic (EHD) thruster
Electrohydrodynamic thruster
An electrohydrodynamic thruster is a high voltage device that propels air or fluids to achieve relative motion. EHD thrusters, unlike ion thrusters, do not carry their own propellant and thus cannot operate in space or vacuum....
, the net force generated by an ion wind device does not rely on the momentum transfer between the charged and the neutral air molecules, but only on the impulse that the charged ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
s gain during their repulsion from the tip. It is analogous to recoil
Recoil
Recoil is the backward momentum of a gun when it is discharged. In technical terms, the recoil caused by the gun exactly balances the forward momentum of the projectile and exhaust gasses, according to Newton's third law...
of a gun
Gun
A gun is a muzzle or breech-loaded projectile-firing weapon. There are various definitions depending on the nation and branch of service. A "gun" may be distinguished from other firearms in being a crew-served weapon such as a howitzer or mortar, as opposed to a small arm like a rifle or pistol,...
when it fires a bullet
Bullet
A bullet is a projectile propelled by a firearm, sling, or air gun. Bullets do not normally contain explosives, but damage the intended target by impact and penetration...
.
See also
- Ion thrusterIon thrusterAn ion thruster is a form of electric propulsion used for spacecraft propulsion that creates thrust by accelerating ions. Ion thrusters are categorized by how they accelerate the ions, using either electrostatic or electromagnetic force. Electrostatic ion thrusters use the Coulomb force and...
- IonocraftIonocraftAn ionocraft or ion-propelled aircraft, commonly known as a lifter or hexalifter, is an electrohydrodynamic device to produce thrust in the air, without requiring any combustion or moving parts. The term "Ionocraft" dates back to the 1960s, an era in which EHD experiments were at their peak...
(AKA Lifter) - EHD thrusterElectrohydrodynamic thrusterAn electrohydrodynamic thruster is a high voltage device that propels air or fluids to achieve relative motion. EHD thrusters, unlike ion thrusters, do not carry their own propellant and thus cannot operate in space or vacuum....
- Hall effect thrusterHall effect thrusterIn spacecraft propulsion, a Hall thruster is a type of ion thruster in which the propellant is accelerated by an electric field. Hall thrusters trap electrons in a magnetic field and then use the electrons to ionize propellant, efficiently accelerate the ions to produce thrust, and neutralize the...
- Magnetoplasmadynamic thrusterMagnetoplasmadynamic thrusterThe Magnetoplasmadynamic thruster is a form of electrically powered spacecraft propulsion which uses the Lorentz force to generate thrust...
- Spacecraft propulsionSpacecraft propulsionSpacecraft propulsion is any method used to accelerate spacecraft and artificial satellites. There are many different methods. Each method has drawbacks and advantages, and spacecraft propulsion is an active area of research. However, most spacecraft today are propelled by forcing a gas from the...
- Field Emission Electric PropulsionField Emission Electric PropulsionField-emission electric propulsion is an advanced electrostatic propulsion concept, a form of ion thruster, that uses liquid metal as a propellant. A FEEP device consists of an emitter and an accelerator electrode...
- Pulsed inductive thrusterPulsed inductive thrusterPulsed inductive thrusters are a form of ion thruster, used in spacecraft propulsion. A PIT uses perpendicular electric and magnetic fields to accelerate a propellant. A nozzle releases a puff of gas which spreads across a flat induction coil of wire about 1 meter across...
- Magnetohydrodynamic driveMagnetohydrodynamic driveA magnetohydrodynamic drive or MHD propulsor is a method for propelling seagoing vessels using only electric and magnetic fields with no moving parts, using magnetohydrodynamics. The working principle involves electrification of the propellant which can then be directed by a magnetic field,...
- Air ioniserAir ioniserAn air ioniser is a device that uses high voltage to ionise air molecules. Negative ions, or anions, are particles with one or more extra electrons, conferring a net negative charge to the particle. Cations are positive ions missing one or more electrons, resulting in a net positive charge...
- List of plasma (physics) applications articles