Degree of ionization
= Degree of ionization
{title2=$\alpha=N_{\rm ion}/N_{\rm nuclei}$}
= Degree of ionisation
{synonym}
The fraction of a specified population of <chemical atoms> that has become ionized. For singly ionized atoms with no external charge source, <charge neutrality> gives equal free-<electron> and ion <number densities>. Its equilibrium value depends on both <temperature> and total <number density> through the <Saha ionization equation>.