Investigations On Fine Spectroscopy Of Doubly-Excited States In Strongly-Correlated Ion Systems

Dielectronic Recombination (DR) is the dominant electron-ion recombina-tion process in many astrophysical and laboratory plasmas. It plays an important role in determining both the level populations and the ionization balance of both high-and low temperature non-local thermal equilibrium (non-LTE) plasmas over a wide range of electron densities and its accurate description is key to spectral analysis, diagnose status of plasma, etc. Heavy-ion storage rings equipped with electron coolers serve as an excellent experimental environment for electron-ion collision studies, which provides high quality ion beam and extremely low temper-ature electron beam in order to obtain high-energy resolution. This thesis studies the processes on the strongly-correlated ion systems based on the heavy-ion stor-age ring CSRm in Lanzhou:In the first chapter, the development process, the research status, and devel-opment tends of DR experiments are reviewed. Furthermore, the main methods and apparatuses for DR experiments are introduced;In the second chapter, the transverse dynamic behavior of ion beam in storage rings and the basic properties of the beam are introduced. The basic dynamic pro-cesses which affect the beam lifetime are analyzed, and the empirical calculation formulas and some examples of ion beam lifetime calculation are given;In the third chapter, the beam measurement principles and diagnostic equip-ments used in the DR experiment are introduced, and the design principles, struc-tures and test results of the YAP and MCP detectors for detection of recombined ions in DR experiments are described in detail;In the fourth chapter, the qualitative description of electronic cooling and quantitative theory of computation so far are summarized. To deeply understand the electronic cooling process, a Monto Carlo integration method is used to calcu- late the electron cooling forces of112Sn35+and58Ni19+ions versus ion longitudinal velocity, and the relative energy of electron-ion collisions in DR experiments is modified according to the simulation.In Chapters V and VI, the fine structure spectroscopy of strongly-correlated many-electron ion systems, i.e., P-like112Sn35+and F-like58Ni19+ions, are investi-gated by the heavy-ion accelerator cooler storage ring CSRm, and the correspond-ing DR rate coefficients and ionic structure information are given. The present re-sults show that for many-electron strongly-correlated ion systems, the complexity of the ion system results in the difficulties of theoretical calculations. In addition, the empirical formula of cross section for radiative recombination (RR) and hydro-genic Rydberg formula are no longer valid. Therefore, the accurate experimental data of rate coefficients for RR and DR are extremely important to study the spectroscopy of astrophysical and fusion plasma, and to diagnose temperatures of electron and ion, and to understand the behavior of Strongly-Correlated Ion systems, etc.Finally, all the works of this thesis are summarized, and the problems in DR experiments as well as prospect trends of DR studies in future are presented.