Quantum statistical approach to the equation of state and the critical point of cesium plasma

The equation of state of a partially ionized plasma is derived within the frame of thermodynamic Green functions. Evaluating the self-energy in a cluster expansion, the formation of bound states is treated in a systematic way. The account of bound states (atoms, dimers) leads to an essential lowering of the critical temperature compared with previous approaches, where the interaction of bound states with free charge carriers via the polarization potential was neglected. Thus, a better agreement with the experimental data is achieved.