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        In the temperature range from 10000K to 10,0000K,

the only species that are present in significant quantities are U1, U1 and electrons. A single reaction accounts for the equilibrium ionization and recombination of these three species.


                    U0 t U'+ + e                   (4.24)

The corresponding Saha equation is


          N+ e      2 7m kT 3/2 u+ _E
                 2 (e e/kT                         (4.25)
           No         h2       uo


The total particle density is NP
                    NTOT -  - = No + N  + e        (4.26)


The charge neutrality is given by N+ =e                                             (4.27)

Using N, = N0, N2 = N+, N  = e, and


                 27rm kT 3/2 U  E0kT
          K = 2     e        +) --e/k
                   h2       U 0

equations (4.25), (4.26) and (4.27) are simplified as


                         N2 Ne   K                 (4.28)
                         N,