Astrophysics (Index)About

ionization fraction

(electron fraction)
(a substance's ratio of unattached electrons to nuclei)

Electron fraction and ionized fraction are generally the ratio of unattached electrons to nuclei. The former is the ratio of unattached electrons to nuclei and molecules, and the latter, the ratio of ions to all nuclei and molecules. The two are sometimes used interchangeably and in the simple/common case of monatomic hydrogen and positive ions, the two would be the same and knowing one is knowing the other, and in this case, the number is also the number of unattached protons. I've seen them symbolized by Ye or xe.


(ionization,hydrogen,plasma)
Further reading:
http://scienceworld.wolfram.com/physics/IonizationFraction.html
http://www.astro.sunysb.edu/dswesty/explode.html

Referenced by page:
r-process

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