New Excitation and Ionization Mechanism of Ions in Dense Plasmas : The Role of Autoionizing States

It is shown that, in dense plasmas, dielectronic capture into doubly excited ionic states followed by the ladderlike excitation-ionization chain becomes important in the excitation-ionization process of ions. For an example of a hydrogenlike ion, its contribution to the excitation 1s..-->..2s, 2p and also to the ionization has been evaluated by the method of the quasisteady-state solution to the rate equations. The increase is found to be substantial, i.e., by more than a factor of 2 both for the excitation and ionization rate coefficients.