| Dielectronic recombination(DR)is an important resonant process in astrophysics and fusion plasmas.Its rate coefficients at the resonance energies is often orders of magnitude larger than that of competing recombination processes,which strongly af-fects the charge state balance,energy-level populations,as well as the radiative spec-trum of plasmas.Hence accurate DR cross sections and rate coefficients are needed for modeling astrophysical and fusion plasmas.On the other hand,DR is also a powerful tool to investigate atomic structure and fundamental effects,such as relativistic effects,QED effects,Breit effects,electron correlations etc.Based on the heavy ion storage ring facilities equipped with electron cooler,a series of DR experiments were carried out with much less background and higher energy resolution at low resonance energy.The corresponding theoretical calculations were completed for better understanding of the experimental spectra as well as exploring the strong electron correlations and QED effects.Firstly,the ?n = 0 DR process of simple structure system including Li-like Xe51+and W71+ ions were investigated using the Atomic Flexible code(FAC)based on the Relativistic configuration interaction method(RCI).The RCI method and formulas to-wards DR process were described systematically on Chapter Two.Then the DR spectra of Li-like Xe51+ ions were calculated by FAC,where the contributions of high Ryd-berg states are obtained by extrapolation method based on the Quantum Defect Theory(QDT).The theoretical rate coefficients,covering the center-of-mass energy range0-505 eV,are in a better agreement with the experimental results measured at the heavy-ion storage ring ESR than the Multi-Configuration Dirac-Fock calculations,especially at the resonance energy range close to the series limits.Lastly the recombiantion process of Li-like W71+ ion,where Tungsten(W,Z=74)was chosen as the plasma-facing ma-terials in the international tokamak reactor International Thermonuclear Experimental Reactor(ITER),was investigated using the same method.And the significant effects of Breit and QED corrections on the energy levels are discussed.The plasma rate coeffi-cients,which are in good agreement with the AUTOSTRUCTURE calculations,were provided to the modeling and diagnosing of fusion plasma(see Chapter Four).Secondly,the relativistic eigenchannel R-matrix method(R-R-Eigen)was further developed towards DR process with enough physical precisions,which based on the an-alytical continuation properties of the short range scattering matrices.And the electron-ion recombination of Be-like Ar14+ ions was investigated using the new method.The detailed introduction of R-R-Eigen method was described in Chapter Five,where are four parts including preparation of target states wavefunctions,Relativistic R-matrix method,multi-channel quantum defect theory(MQDT)and autoionization and radia-tive rates.Then a full calculations of the J?= 1.5+ symmetry of highly charged Ar13+ions by R-R-Eigen code was completed.With the high accurate scatter matrix parame-ters,all energy levels in discrete energy regions were obtained by applying the MQDTprocedures.The resonance positions and widths of the autoionization states were alsolisted by the maxima of the energy derivatives of the eigenphase shift.This work is a crucial part of the future DR study,and showed the big significance of the electron correlations on the highly charged ions(HCIs)(see Chapter Six).Finally,considering the contributions from 0.5?7.51 symmetries,the preliminary recombination rates of Be-like Ar14+ ions are given,which showed a better agreement with the experimen-tal spectra at CSRm than the AUTOSTRUCTURE results near the threshold(<0.5eV).The corresponding resonance states and strengths,which are contributing to the strong TR contributions,were discussed.This work showed that the R-R-Eigen method is a reliable way to treat the DR process,especially for the system with strong electron correlations. |
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