The complete refractive index of partially ionised dense gases

The usual expressions for the complex refractive index of a plasma are derived from mean-free-path-type formulae. They are not able to distinguish precisely between the mutual influence of electron-ion and electron-atom collisions and they ignore totally electron-electron collisions and electrostatic correlation effects, which are important in dense plasmas. In the frame of the kinetic transport theory more accurate expressions are obtained. It is shown that the difference can amount to 30% for the imaginary part of the refractive index of a dense argon plasma. (author)