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## Debye lengthThe notion of ## Additional recommended knowledgeIn plasma physics, the In space plasmas where the electron density is relatively low, the Debye length may reach macroscopic values, such as in the magnetosphere, solar wind, interstellar medium and intergalactic medium (see table):
The Particle Kinetics of Plasmahttp://www.pma.caltech.edu/Courses/ph136/yr2002/ Hannes Alfven pointed out that: "In a low density plasma, localized space charge regions may build up large potential
drops over distances of the order of some tens of the Debye lengths. Such regions have been called ## Debye length in a plasmaIn a plasma, the Debye length is where - λ
_{D}is the Debye length, - ε
_{0}is the permittivity of free space, -
*k*is Boltzmann's constant, -
*q*_{e}is the charge on an electron, -
*T*and_{e}*T*are the temperatures of the electrons and ions, respectively,_{i} -
*n*is the density of electrons,_{e} -
*n*is the density of atomic species_{ij}'*i*, with positive ionic charge*jq*_{e}
The ion term is often dropped, giving although this is only valid when the ions are much colder than the electrons. ## Debye length in an electrolyteIn an electrolyte or a colloidal dispersion, the Debye length is usually denoted with symbol where -
*I*is the ionic strength of the electrolyte, - ε
_{0}is the permittivity of free space, - ε
_{r}is the dielectric constant, -
*k*is the Boltzmann's constant, -
*T*is the absolute temperature in kelvins, -
*N*is Avogadro's number._{A} -
*e*is the elementary charge,
or when the solute is mono-monovalent and symmetrical, where -
*R*is the gas constant, -
*F*is the Faraday constant, -
*C*_{0}is the molar concentration of the electrolyte.
Alternatively, where - λ
_{B}is the Bjerrum length of the medium.
For water at room temperature, ## References- Goldston & Rutherford (1997).
*Introduction to Plasma Physics*. Institute of Physics Publishing, Philadelphia.
- Lyklema (1993).
*Fundamentals of Interface and Colloid Science*. Academic Press, NY.
Categories: Colloidal chemistry | Plasma physics | Electrochemistry |
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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Debye_length". A list of authors is available in Wikipedia. |