Effective temperatures in hot dense plasmas

In medium- and high-Z hot dense non-local thermodynamic equilibrium plasmas a standard level-by-level collisional-radiative model cannot be used because of the excessive number of levels involved. Gathering the levels into large ensembles is a convenient way for reducing the complexity of the calculations. A review is given of these approaches, whereby effective temperatures have been evidenced, and calculated ab initio. Numerical examples are presented in germanium and gold plasmas. The physical origin of these temperatures is discussed.