Plasma contactors are devices used on
spacecraft
A spacecraft is a vehicle that is designed spaceflight, to fly and operate in outer space. Spacecraft are used for a variety of purposes, including Telecommunications, communications, Earth observation satellite, Earth observation, Weather s ...
in order to prevent accumulation of
electrostatic
Electrostatics is a branch of physics that studies slow-moving or stationary electric charges.
Since classical times, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word (), mean ...
charge through the expulsion of
plasma (often
Xenon
Xenon is a chemical element; it has symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...
).
An electrical
contactor is an electrically controlled switch which closes a power or high voltage
electrical circuit
An electrical network is an interconnection of electrical components (e.g., battery (electricity), batteries, resistors, inductors, capacitors, switches, transistors) or a model of such an interconnection, consisting of electrical elements (e. ...
. A plasma contactor changes the electrically insulating vacuum into a conductor by providing movable electrons and
positive gas ions. This conductive path closes a
phantom loop circuit to discharge or neutralize the
static electricity
Static electricity is an imbalance of electric charges within or on the surface of a material. The charge remains until it can move away by an electric current or electrical discharge. The word "static" is used to differentiate it from electric ...
that can build up on a spacecraft.
Space contains regions with varying concentrations of charged particles such as the
plasma sheet, and a static charge builds up as the spacecraft moves between these regions, or as the electrical potential varies within such a region.
Static electricity may also build up on a spacecraft as a result of space
radiation
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. This includes:
* ''electromagnetic radiation'' consisting of photons, such as radio waves, microwaves, infr ...
, including sunlight, depending on the materials used on the surfaces of the spacecraft.
A plasma contactor is mounted on the Z1 segment of the
International Space Station
The International Space Station (ISS) is a large space station that was Assembly of the International Space Station, assembled and is maintained in low Earth orbit by a collaboration of five space agencies and their contractors: NASA (United ...
Integrated Truss Structure
The Integrated Truss Structure (ITS) of the International Space Station (ISS) consists of a linear arranged sequence of connected trusses on which various unpressurized components are mounted such as logistics carriers, radiators, ISS Solar Arra ...
.
References
*
*
*
* Michael J. Patterso
"Cathodes Delivered for Space Station Plasma Contactor System,"''Research And Technology 1998,'' NASA Technical Report TM-1999-208815, NASA Glenn Research Center (retrieved 30 November 2012)
Plasma technology and applications
Spacecraft components
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