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Abstract

This thesis focuses on studying the K-shell dielectronic recombination (DR) of highly charged oxygen ions using the PolarX electron beam ion trap. The aim is to measure absolute dielectronic resonance strengths. The x-ray spectrum was recorded for different electron beam energies, trap depths, and beam currents. The charge state distribution was also measured for each parameter combination using the ion extraction system. To determine the electron and ion space charge, we observed the apparent shift of the resonance energies with the electron beam current and trap depth. This helped us find the compensation factor for the negative space charge of the electron beam by the positive ion space charge. We used these values to infer the DR resonance energies, electron beam radius, and electron current density. We determined the absolute number of trapped ions by using the compensation factor, along with an independent measurement with a Faraday cup setup. We also estimated the overlap between the ion cloud and the electron beam using the space-charge-based electron beam radius and gyromagnetic radius of the trapped ions. Using these inferred parameters with the fitted X-ray line intensities, we determined the DR resonance strengths for selected resonances and compared them to distorted wave calculations using the FLEXIBLE ATOMIC CODE. The accurate measurements of the DR strengths are of interest to test atomic theory and beneficial for modeling of astrophysical and laboratory hot plasmas.