Thermophysics Characterization of Multiply Ionized Air Plasma Absorption of Laser Radiation

Thermodynamic properties of multiply ionized air plasma atoms are computed using hydrogenic approximation of the electronic partition function for temperatures up to 1,500,000K, to study the impact of multiple ionization of air plasma on the inverse Bremsstrahlung absorption of laser radiation. Three formulas of inverse Bremsstrahlung absorption are investigated, and a general electron-ion inverse Bremsstrahlung formula is derived for multispecies, multiple ionization absorption. The computed double ionization absorption coefficients agree reasonably well with those of literature for 1, 10, and 100 atm. The importance of multiple ionization modeling is demonstrated by finding that the area under the full ionization absorption curve is twice that of single ionization. The effect of pressure on fully ionized air plasma absorption is computed for five pressures: 0.01, 0.1, 1, 10, and 100 atm.