Photon Energy Grid

The elemental opacities are calculated on a uniform grid of temperatures, electron degeneracy paramaters and dimensionless photon energies u, where u is defined as:

u = hv / kT

hv is the photon energy in eV and kT is the temperature in eV. The u grid is selected instead of the photon energy grid because the same u grid can be used for all temperatures and cover the important photon energy ranges needed to integrate the Rosseland and Planck "gray" opacities. These photon energy ranges would be 0. - 20. eV for a temperature of 1. eV and 0. - 2000. eV for a 100. eV temperature. For the u grid, the range would be 0. - 20. for both temperatures.

u Grid used on the Web Page

The opacities are calculated on a grid of 14,900 u points for each temperature point. This grid is shown below:

  u Values      14,900 Point Grid
 _________  ___________________________
      0.0
       |
       |    9600 points, steps of .00125
       |
     12.5
       |
       |    1600 points, steps of .005
       |
     20.0
       |
       |    1000 points, steps of .01
       |
     30.0
       |
       |     700 points, steps of .1
       |
    100.0
       |
       |     900 points, steps of 1.0
       |
   1000.0
       |
       |     900 points, steps of 10.0
       |
  10000.0
       |
       |     200 points, steps of 100.0
       |
  30000.0
           _____
           14900 points