Plasma (physics)

Top: Lightning and neon lights are commonplace generators of plasma. Center left: A plasma globe, illustrating some of the more complex plasma phenomena, including filamentation. Center right: A plasma trail from the Space Shuttle Atlantis during re-entry into Earth's atmosphere, as seen from the International Space Station. Bottom left: A fire in a fire pit; fires may produce plasma if hot enough. Bottom right: The Sun's corona as seen from a solar eclipse in France.

Plasma (from Ancient Greek πλάσμα (plásma) 'moldable substance'[1]) is one of four fundamental states of matter (the other three being solid, liquid, and gas) characterized by the presence of a significant portion of charged particles in any combination of ions or electrons. It is the most abundant form of ordinary matter in the universe, mostly in stars (including the Sun), but also dominating the rarefied intracluster medium and intergalactic medium.[2][3][4][5] Plasma can be artificially generated, for example, by heating a neutral gas or subjecting it to a strong electromagnetic field.[6]

The presence of charged particles makes plasma electrically conductive, with the dynamics of individual particles and macroscopic plasma motion governed by collective electromagnetic fields and very sensitive to externally applied fields.[7] The response of plasma to electromagnetic fields is used in many modern devices and technologies, such as plasma televisions or plasma etching.[8]

Depending on temperature and density, a certain number of neutral particles may also be present, in which case plasma is called partially ionized. Neon signs and lightning are examples of partially ionized plasmas.[9] Unlike the phase transitions between the other three states of matter, the transition to plasma is not well defined and is a matter of interpretation and context.[10] Whether a given degree of ionization suffices to call a substance "plasma" depends on the specific phenomenon being considered.

  1. ^ Liddell, Henry George; Scott, Robert (1940). "πλάσμα". A Greek-English Lexicon. Clarendon Press. Retrieved 10 February 2023.
  2. ^ Chu, P.K.; Lu, XinPel (2013). Low Temperature Plasma Technology: Methods and Applications. CRC Press. p. 3. ISBN 978-1-4665-0990-0.
  3. ^ Piel, A. (2010). Plasma Physics: An Introduction to Laboratory, Space, and Fusion Plasmas. Springer. pp. 4–5. ISBN 978-3-642-10491-6. Archived from the original on 5 January 2016.
  4. ^ Phillips, K. J. H. (1995). Guide to the Sun. Cambridge University Press. p. 295. ISBN 978-0-521-39788-9. Archived from the original on 15 January 2018.
  5. ^ Aschwanden, M. J. (2004). Physics of the Solar Corona. An Introduction. Praxis Publishing. ISBN 978-3-540-22321-4.
  6. ^ Chiuderi, C.; Velli, M. (2015). Basics of Plasma Astrophysics. Springer. p. 17. ISBN 978-88-470-5280-2.
  7. ^ Morozov, A.I. (2012). Introduction to Plasma Dynamics. CRC Press. p. 30. ISBN 978-1-4398-8132-3.
  8. ^ Chu, P.K.; Lu, XinPel (2013). Low Temperature Plasma Technology: Methods and Applications. CRC Press. ISBN 978-1-4665-0990-0.
  9. ^ "How Lightning Works". HowStuffWorks. April 2000. Archived from the original on 7 April 2014.
  10. ^ Morozov, A.I. (2012). Introduction to Plasma Dynamics. CRC Press. p. 4−5. ISBN 978-1-4398-8132-3.