Plasma contactors are devices used on

spacecraft A spacecraft is a vehicle or machine designed to fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, p ...

in order to prevent accumulation of

electrostatic Electrostatics is a branch of physics that studies electric charges at rest (static electricity). Since classical times, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word for amber ...

charge Charge or charged may refer to: Arts, entertainment, and media Films * '' Charge, Zero Emissions/Maximum Speed'', a 2011 documentary Music * ''Charge'' (David Ford album) * ''Charge'' (Machel Montano album) * ''Charge!!'', an album by The Aqu ...

through the expulsion 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 ...

(often

Xenon Xenon is a chemical element with the 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 :''In semiconductor testing, contactors can also be referred to as the specialized socket that connects the device under test.'' :''In process industries, a contactor is a vessel where two streams interact, for example, air and liquid. See Gas- ...

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., batteries, resistors, inductors, capacitors, switches, transistors) or a model of such an interconnection, consisting of electrical elements (e.g., voltage sources, ...

. 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 In telecommunication and electrical engineering, a phantom circuit is an electrical circuit derived from suitably arranged wires with one or more conductive paths being a circuit in itself and at the same time acting as one conductor of another circ ...

circuit to discharge or neutralize the

static electricity Static electricity is an imbalance of electric charges within or on the surface of a material or between materials. The charge remains until it is able to move away by means of an electric current or electrical discharge. Static electricity is na ...

that can build up on a spacecraft. Space contains regions with varying concentrations of charged particles such as the

plasma sheet In the magnetosphere, the plasma sheet is a sheet-like region of denser (0.3-0.5 ions/cm3 versus 0.01-0.02 in the lobes) hot plasma and lower magnetic field near the equatorial plane, between the magnetosphere's north and south lobes. A magneto ...

, 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 through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visi ...

, 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 the largest modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA ...

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, solar arrays, ...

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 physics Spacecraft components {{spacecraft-stub

See also

References