
Ion wind, ionic wind, corona wind or electric wind is the airflow induced by electrostatic forces linked to
corona discharge
A corona discharge is an electrical discharge caused by the ionization of a fluid such as air surrounding a conductor carrying a high voltage. It represents a local region where the air (or other fluid) has undergone electrical breakdown ...
arising at the tips of some sharp conductors (such as points or blades) subjected to high voltage relative to ground. Ion wind is an
electrohydrodynamic
Electrohydrodynamics (EHD), also known as electro-fluid-dynamics (EFD) or electrokinetics, is the study of the dynamics of electrically charged fluids. It is the study of the motions of ionized particles or molecules and their interactions with e ...
phenomenon. Ion wind generators can also be considered
electrohydrodynamic thruster
An ion-propelled aircraft or ionocraft is an aircraft that uses electrohydrodynamics (EHD) to provide lift or thrust in the air without requiring combustion or moving parts. Current designs do not produce sufficient thrust for manned flight or us ...
s.
The term "ionic wind" is considered a
misnomer
A misnomer is a name that is incorrectly or unsuitably applied. Misnomers often arise because something was named long before its correct nature was known, or because an earlier form of something has been replaced by a later form to which the name ...
due to misconceptions that only positive and negative ions were primarily involved in the phenomenon. A 2018 study found that electrons play a larger role than the negative ions during the negative voltage period. As a result, the term "electric wind" has been suggested as a more accurate terminology.
This phenomenon is now used in an
MIT ionic wind plane, the first solid state plane, developed in 2018.
History
B. Wilson in 1750 demonstrated the recoil force associated to the same corona discharge and precursor to the
ion thruster was the corona discharge pinwheel. The corona discharge from the freely rotating pinwheel arm with ends bent to sharp points gives the air a space charge which repels the point because the polarity is the same for the point and the air.
Francis Hauksbee, curator of instruments for the
Royal Society of London
The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...
, 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.
In 2018, researchers from South Korea and Slovenia used
Schlieren photography to experimentally determine that electrons, in addition to ions, play an important role in generating ionic wind. The study was the first to provide direct evidence that the
electrohydrodynamic
Electrohydrodynamics (EHD), also known as electro-fluid-dynamics (EFD) or electrokinetics, is the study of the dynamics of electrically charged fluids. It is the study of the motions of ionized particles or molecules and their interactions with e ...
force responsible for the ionic wind is caused by a charged particle drag that occur as the electrons and ions push the neutral particles away.
In 2018, a team of
MIT researchers built and successfully flew the first-ever prototype plane propelled by ionic wind,
MIT EAD Airframe Version 2.
Mechanism
Net electric charges on conductors, including local charge distributions associated with dipoles, reside entirely on their external surface (see
Faraday cage
A Faraday cage or Faraday shield is an enclosure used to block electromagnetic fields. A Faraday shield may be formed by a continuous covering of conductive material, or in the case of a Faraday cage, by a mesh of such materials. Faraday cage ...
), and tend to concentrate more around sharp points and edges than on flat surfaces. This means that the
electric field
An electric field (sometimes E-field) is the physical field that surrounds electrically charged particles and exerts force on all other charged particles in the field, either attracting or repelling them. It also refers to the physical field fo ...
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
An electric field (sometimes E-field) is the physical field that surrounds electrically charged particles and exerts force on all other charged particles in the field, either attracting or repelling them. It also refers to the physical field fo ...
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
Plasma or plasm may refer to:
Science
* Plasma (physics), one of the four fundamental states of matter
* Plasma (mineral), a green translucent silica mineral
* Quark–gluon plasma, a state of matter in quantum chromodynamics
Biology
* Blood pla ...
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. An opposite force acts on the tip that may recoil if not tight to ground.
A
vaneless ion wind generator performs the inverse function, using ambient wind to move ions, which are collected yielding electrical energy.
See also
*
Air ioniser
An air ioniser (or negative ion generator or Chizhevsky's chandelier) is a device that uses high voltage to ionise (electrically charge) air molecules. Negative ions, or anions, are particles with one or more extra electrons, conferring a net ne ...
*
Ion thruster
*
Ionocraft
An ion-propelled aircraft or ionocraft is an aircraft that uses electrohydrodynamics (EHD) to provide lift or thrust in the air without requiring combustion or moving parts. Current designs do not produce sufficient thrust for manned flight or us ...
*
Plasma actuator
Plasma or plasm may refer to:
Science
* Plasma (physics), one of the four fundamental states of matter
* Plasma (mineral), a green translucent silica mineral
* Quark–gluon plasma, a state of matter in quantum chromodynamics
Biology
* Blood pla ...
*
Hall-effect thruster
In spacecraft propulsion, a Hall-effect thruster (HET) is a type of ion thruster in which the propellant is accelerated by an electric field. Hall-effect thrusters (based on the discovery by Edwin Hall) are sometimes referred to as Hall thruster ...
*
Magnetohydrodynamic drive
A magnetohydrodynamic drive or MHD accelerator is a method for propelling vehicles using only electric and magnetic fields with no moving parts, accelerating an electrically conductive propellant ( liquid or gas) with magnetohydrodynamics. The ...
*
Magnetoplasmadynamic thruster
A magnetoplasmadynamic (MPD) thruster (MPDT) is a form of electrically powered spacecraft propulsion which uses the Lorentz force (the force on a charged particle by an electromagnetic field) to generate thrust. It is sometimes referred to as L ...
*
Pulsed inductive thruster
*
Field-emission electric propulsion
Field-emission electric propulsion (FEEP) is an advanced electrostatic space propulsion concept, a form of ion thruster, that uses a liquid metal as a propellant – usually either caesium, indium, or mercury.
A FEEP device consists of an emitte ...
*
Spacecraft propulsion
Spacecraft propulsion is any method used to accelerate spacecraft and artificial satellites. In-space propulsion exclusively deals with propulsion systems used in the vacuum of space and should not be confused with space launch or atmospheric e ...
*
List of plasma (physics) articles
This is a list of plasma physics topics.
A
* Ablation
* Abradable coating
* Abraham–Lorentz force
* Absorption band
* Accretion disk
* Active galactic nucleus
* Adiabatic invariant
* ADITYA (tokamak)
* Aeronomy
* Afterglow plasma
* Airg ...
*
Solid-state fan A solid-state fan is a device used to produce an airflow with no moving parts. Such a device may use the principle of electro-aerodynamic pumping, which is based on corona discharge
A corona discharge is an electrical discharge caused by th ...
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References
External links
Plasma propulsion in space
Plasma physics
Spacecraft propulsion
Electrostatics