Ionic fraction data
Arnaud and Rothenflug (1985) - Helium

LOG T   +0      +1      +2

4.0     0.00    -9.05         
4.1     0.00    -6.10         
4.2     0.00    -3.75         
4.3     0.00    -2.12         
4.4     -0.07   -0.84   -8.78
4.5     -0.51   -0.16   -5.79
4.6     -1.33   -0.02   -3.68
4.7     -2.07   -0.01   -2.17
4.8     -2.63   -0.05   -0.99
4.9     -3.20   -0.34   -0.26
5.0     -3.94   -0.96   -0.05
5.1     -4.67   -1.60   -0.01
5.2     -5.32   -2.16   0.00
5.3     -5.90   -2.63   0.00
5.4     -6.42   -3.03   0.00
5.5     -6.90   -3.38   0.00
5.6     -7.33   -3.68   0.00
5.7     -7.73   -3.94   0.00