Dieletronic Recombination Experiment With Astrophysical Relevant Highly Charged Ions

Dielectronic recombination(DR)is one of the fundamental mechanisms in the as-trophysical and fusion plasmas.Recombination rate coefficients are essential for cal-culating the charge state distribution and line radiations in a plasma.Storage rings equipped with electron coolers are ideal platforms to perform high-resolution electron-ion collision experiments.Accurate DR rate coefficients obtained from a stroage ring experiments can serve as a benchmark for astrophysics and fusion science.The compar-ison between the experimental results and theoretical calculations can provide a strin-gent test of the theoretical models and computational codes.The research work associ-ated with this thesis is based on the Heavy-ion Research Facility in Lanzhou.DR rate coefficients of astrophysical relevant Be-like Ca and F-like Ni ions have been studied by means of merged-beam method at the CSRm.DR measurement is performed for the first time at the CSRe with the newly developed particle detector of multi-wire propor-tional chamber(MWPC).The agreement between the experimental results at the CSRe and the CSRm as well as the theoretical calculations indacates the reliablity of the DR paltform at the CSRe.The main contents of this thesis are summarized as following:1?DR rate coefficients of Be-like Ca and F-like Ni ions have been memasured by means of merged-beam method at the HIRFL-CSRm.The plasma recombination rate coefficients have also been deduced from the measured data.It is found that the trielec-tronic recombination(TR)has a prominent contribution at low collision energies for Be-like Ca and the theoretical calculation with the AUTOSTRUCTURE code underes-timates the TR rate coefficients.Several observed features below 2.5 eV are attributed to the parent ions at the long-lived metastable state.Configurations of these features are recognized for further precision spectroscopy study for QED test and life time mea-surement.The DR resonance features are well resolved for F-like Ni,and the fitted resonance positions and strengths are compared with the FAC calculations in details.The comparison shows that the calculation still cannot produce the DR resonances near the threshold with a sufficient accuracy.The experimentally derived plasma recombi-nation rate coefficients are compared with the present and previous theoretical data,and the experimental data are evaluated as the recommended benchmarks for use in plasma models;2?A set of particle detector and data acquisition system based on the MWPC is constructed for DR experiment at the CSRe.First DR experiment at the CSRe was performed with the newly developed MWPC particle detector.The measured DR rate coefficients for Na-like Kr at the CSRe agree well with the data measured data at the CSRm,which indicates the reliablity of the DR research at the CSRe and paves the way for future DR experiments at the CSRe.In addition to being as a counter,MWPC can also serve as a beam profile monitor in real time with the obtained position signals.The ion beam diameter of the CSRe was optimized to less than 4 mm,which has reached an international level.