Electrostatic motor
Encyclopedia
An electrostatic motor or capacitor motor is a type of electric motor
based on the attraction and repulsion of electric charge
.
Often, electrostatic motors are the dual
of conventional coil-based motors. They typically require a high voltage power supply, although very small motors employ lower voltages. Conventional electric motors instead employ magnetic attraction and repulsion, and require high current at low voltages. In the 1750s, the first electrostatic motors were developed by Benjamin Franklin
and Andrew Gordon. Today the electrostatic motor finds frequent use in micro-mechanical (MEMS
) systems where their drive voltages are below 100 volts, and where moving charged plates are far easier to fabricate than coils and iron cores.
An alternative type of electrostatic motor is the spacecraft electrostatic ion drive thruster where forces and motion are created by electrostatically accelerating ions.
Also, the molecular machinery which runs living cells is often based on linear and rotary electrostatic motors.
, recently developed rotational bearings based upon multiwall carbon nanotubes. By attaching a gold plate (with dimensions of the order of 100 nm) to the outer shell of a suspended multiwall carbon nanotube (like nested carbon cylinders), they are able to electrostatically rotate the outer shell relative to the inner core. These bearings are very robust; devices have been oscillated thousands of times with no indication of wear. These nanoelectromechanical systems (NEMS) are the next step in miniaturization and may find their way into commercial applications in the future.
Gridded electrostatic ion thruster
s commonly utilize xenon
gas. This gas has no charge and is ionized
by bombarding it with energetic electrons. These electrons can be provided from a hot cathode
filament and accelerated in the electrical field of the cathode fall to the anode (Kaufman type ion thruster). Alternatively, the electrons can be accelerated by the oscillating electric field induced by an alternating magnetic field of a coil, which results in a self-sustaining discharge and omits any cathode (radiofrequency ion thruster).
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Electric motor
An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...
based on the attraction and repulsion of electric charge
Electric charge
Electric charge is a physical property of matter that causes it to experience a force when near other electrically charged matter. Electric charge comes in two types, called positive and negative. Two positively charged substances, or objects, experience a mutual repulsive force, as do two...
.
Often, electrostatic motors are the dual
Dual (electronics)
In physics, the electromagnetic dual concept is based on the idea that, in the static case, electromagnetism has two separate facets: electric fields and magnetic fields. Expressions in one of these will have a directly analogous, or dual, expression in the other...
of conventional coil-based motors. They typically require a high voltage power supply, although very small motors employ lower voltages. Conventional electric motors instead employ magnetic attraction and repulsion, and require high current at low voltages. In the 1750s, the first electrostatic motors were developed by Benjamin Franklin
Benjamin Franklin
Dr. Benjamin Franklin was one of the Founding Fathers of the United States. A noted polymath, Franklin was a leading author, printer, political theorist, politician, postmaster, scientist, musician, inventor, satirist, civic activist, statesman, and diplomat...
and Andrew Gordon. Today the electrostatic motor finds frequent use in micro-mechanical (MEMS
Microelectromechanical systems
Microelectromechanical systems is the technology of very small mechanical devices driven by electricity; it merges at the nano-scale into nanoelectromechanical systems and nanotechnology...
) systems where their drive voltages are below 100 volts, and where moving charged plates are far easier to fabricate than coils and iron cores.
An alternative type of electrostatic motor is the spacecraft electrostatic ion drive thruster where forces and motion are created by electrostatically accelerating ions.
Overview
An electrostatic motor is based on the attraction and repulsion of electric charge. Usually, electrostatic motors are the dual of conventional coil-based motors. They typically require a high voltage power supply, although very small motors employ lower voltages. Conventional electric motors instead employ magnetic attraction and repulsion, and require high current at low voltages. In the 1750s, the first electrostatic motors were developed by Benjamin Franklin and Andrew Gordon. Today the electrostatic motor finds frequent use in micro-mechanical (MEMS) systems where their drive voltages are below 100 volts, and where moving, charged plates are far easier to fabricate than coils and iron cores.Also, the molecular machinery which runs living cells is often based on linear and rotary electrostatic motors.
Nanotube nanomotor
Researchers at University of California, BerkeleyUniversity of California, Berkeley
The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...
, recently developed rotational bearings based upon multiwall carbon nanotubes. By attaching a gold plate (with dimensions of the order of 100 nm) to the outer shell of a suspended multiwall carbon nanotube (like nested carbon cylinders), they are able to electrostatically rotate the outer shell relative to the inner core. These bearings are very robust; devices have been oscillated thousands of times with no indication of wear. These nanoelectromechanical systems (NEMS) are the next step in miniaturization and may find their way into commercial applications in the future.
Electrostatic ion drive
Electric motors, in general, produce motion when powered by electric currents. The common type of spacecraft ion drive uses electrostatic forces to accelerate ions to generate forces to create motion, and thus can be considered as unconventional electric motors.Gridded electrostatic ion thruster
Electrostatic ion thruster
An electrostatic ion thruster is a design for ion thrusters . These designs use high voltage electrodes in order to accelerate ions with electrostatic forces.-History:...
s commonly utilize xenon
Xenon
Xenon is a chemical element with the symbol Xe and atomic number 54. The element name is pronounced or . A colorless, heavy, odorless noble gas, xenon occurs in the Earth's atmosphere in trace amounts...
gas. This gas has no charge and is 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...
by bombarding it with energetic electrons. These electrons can be provided from a hot cathode
Cathode
A cathode is an electrode through which electric current flows out of a polarized electrical device. Mnemonic: CCD .Cathode polarity is not always negative...
filament and accelerated in the electrical field of the cathode fall to the anode (Kaufman type ion thruster). Alternatively, the electrons can be accelerated by the oscillating electric field induced by an alternating magnetic field of a coil, which results in a self-sustaining discharge and omits any cathode (radiofrequency ion thruster).
Patents
The prime classifications of electrostatic motors by the USPTO are:- Class 310 ELECTRICAL GENERATOR OR MOTOR STRUCTURE
- 300 NON-DYNAMOELECTRIC
- 308 Charge accumulating
- 309 Electrostatic
- 300 NON-DYNAMOELECTRIC
- -- J. Gallegos -- "Static electric Machine"
- -- E. ThomsonElihu ThomsonElihu Thomson was an American engineer and inventor who was instrumental in the founding of major electrical companies in the United States, the United Kingdom and France.-Early life:...
-- "Electrostatic motor" - -- Harold B. Smith -- "Apparatus for transforming electrical energy into mechanical energy"
- -- W. G. Cady -- "Electromechanical System"
- —- T. T. BrownThomas Townsend BrownThomas Townsend Brown was an American physicist.-Early and middle years:Brown was born in Zanesville, Ohio; his parents were Lewis K. and Mary Townsend Brown. In 1921, Brown discovered what was later called the Biefeld-Brown effect while experimenting with a Coolidge X-ray tube. This is a vacuum...
-- "Electrostatic motor" (1934-09-25) - -- B. Bollee -- "Electrostatic Motor" (ed. Electrostatics from Atmospheric ElectricityAtmospheric electricityAtmospheric electricity is the regular diurnal variations of the Earth's atmospheric electromagnetic network . The Earth's surface, the ionosphere, and the atmosphere is known as the global atmospheric electrical circuit...
) - -- B. Bollee -- "Electrostatic Motor"
- -- MITSUBISHI CHEM CORP -- "Electrostatic actuator"
- -- Robert, et al. -- "Electrostatic Motor"
See also
- Electrostatic generatorElectrostatic generatorAn electrostatic generator, or electrostatic machine, is a mechanical device that produces static electricity, or electricity at high voltage and low continuous current...
- Molecular motorsMolecular motorsMolecular motors are biological molecular machines that are the essential agents of movement in living organisms. Generally speaking, a motor may be defined as a device that consumes energy in one form and converts it into motion or mechanical work; for example, many protein-based molecular motors...
- NanomotorNanomotorA nanomotor is a molecular device capable of converting energy into movement. It can typically generate forces on the order of piconewtons.A proposed branch of research is the integration of molecular motor proteins found in living cells into molecular motors implanted in artificial devices...
External articles and further reading
- de Queiroz, Antonio Carlos M., "An Electrostatic Linear Motor". 24 January 2002.
- C.L. Stong, "Electrostatic Motors Are Powered By Electric Field of the Earth", October 1974.
- William J. Beaty, "Simple Electrostatic Motor".
- "ElectrostaticMotor". tm.net.
- Fast and Flexible Electrostatic Motors at Univ. Tokyo"http://www.aml.t.u-tokyo.ac.jp/movies/research/demed.mpg".
- Heavy Lifting Electrostatic Motors at Univ. Tokyo"http://www.aml.t.u-tokyo.ac.jp/movies/es_motor/demed.mov".
- E. Sarajlic et al., MEMS electrostatic micromotors http://christophe.yamahata.fr/?page=project_details&ID=53&lng=en
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