Screening and collective effects on electron-impact excitation of hydrogen-like ions in nonideal plasmas

Plasma screening and nonideal collective effects on the electron-impact excitation of hydrogen-like ions are investigated in nonideal plasmas. The interaction potential in nonideal plasmas is given by the pseudopotential model, taking into account the screening effect as well as the collective effect. The screened radial atomic wavefunctions and energy eigenvalues for the 1s and 2p states of the hydrogen-like target ions in nonideal plasmas are obtained by the variational principle and perturbational method. The analytic form of the screened Coulomb focusing factor is obtained, including the plasma screening and nonideal collective effects in order to investigate the correct behaviour of the excitation cross section near the excitation threshold. The excitation cross section including the screening, collective, and Coulomb focusing effects are obtained as a function of the nonideality plasma parameter, Debye length and kinetic energy of the projectile electron. It is found that the scaled 1s → 2p excitation cross sections including the plasma screening and collective effects are found to decrease with increasing the nonideality plasma parameter.