Optimization Of Shanghai EBIT Device

Highly Charged Ion (HCI) is an important form of matter existing in the universe. Through the atomic processes and spectroscopic studies of HCIs, it provides us with an powerful diagnostic tool for precisely investigations of hot plasmas such as temperature, density, electromagnetic field, as well as ion motion.Electron Beam Ion Trap (EBIT) is one of the techniques to produce HCIs in the laboratory. It bases on electron impact ionization and electromagnetic confinement of the HCIs. An EBIT can function as both a light source and an ion source, which in principle can produce any charge stage of any element. In an EBIT the electron beam is quasi mono-energetic, which is conducive to dividually study the atomic processes in the plasma.Shanghai-EBIT was the first and the only EBIT facility in China, which generated an electron beam in 2005. After four years of operation, it was found that some improvements/modifications to the old machine were necessary, and then it was forced to shut down in June,2009. Finally, with more than three years of efforts, the redesigned Shanghai-EBIT had been back online and got its first stable beam line in early 2013. The main task for this thesis is the optimization, improvement to the old machine, and some initial tests, preliminary experimental studies with the redesigned new one, which includes:Ⅰ. Redesign of the old Shanghai-EBIT, includes:the design of the supercon-duction system, cryogenic system, ultra high vacuum system; selection of the main material; evaluation and protection of the high voltage platform; system alignment of the beam optics.Ⅱ. Test of each subsystem, includes:the simulation of the beam optics; the highest magnetic field and its uniformity, cooling down of the cryogenic system; leak detection, baking, ultimate pressure of the vacuum system after cooling; test of the gas injection system; the ultimate concentricity measurement of the system alignment in different operating conditions. Initial tests show that each subsystem of the redesigned Shanghai-EBIT has high efficiency and stability.Ⅲ. The overall performance of the redesigned Shanghai-EBIT and the phys-ical experimental research, includes:the electron beam optimization; the electron beam width and density diagnoses; the electron beam energy distribution; the Au ions injection tests from the MEVVA ion source; the study of the first inter-shell (KLL) dielectronic recombination processes for He-up to O-like Tungsten. Preliminary experimental studies show that the redesigned Shanghai-EBIT has excellent performance.Currently, for the performance reasons of the electron gun cathode, the elec-tron beam density and current intensity haven’t reach the expected value. The spare 200 kV high voltage power supply hasn’t been purchased, which means there will be some limitation for the raising of the electron energy. The injection effi-ciency of the MEVVA ion source in certain high energy condition is not as good as expected. Some improvements for the ion transportation are necessary in the future.