Electron Beam Ion Traps (EBIT) can be used to create highly charged ions (HCI) of almost any charged state by simply tuning the energy of the electron beam. Atomic spectroscopy with EBITs, therefore, offers a great platform to identify previously unmeasured transitions, understand atomic processes in laboratory and astrophysical plasmas, and explore the structure of unique electron configurations to benchmark modern atomic theories. An interesting case of the latter is the fine structure 3d9 2D3/2 - 2D5/2 transitions in Co-like ions with suppressed correlations and enhanced relativistic and quantum electrodynamics (QED) effects *, **. These transitions, also labeled as "Layzer quenched" transitions, can be used to accurately test current methods to compute Breit and QED effects. Here, we present direct measurements of the 3d9 2D3/2 - 2D5/2 fine structure of Co-like Yb, Re, Os, and Ir using the National Institute of Standards and Technology (NIST) EBIT facility. Comparisons with the existing theories ***, **** are made in an effort to understand the Briet interaction and the self-energy contribution to QED.

Spectral analysis of an EBIT plasma requires an understanding of the ionization balance. Simulations require accurate atomic data (excitation, ionization, and recombination cross sections) and known operating conditions (electron beam density and energy, and trapped ion temperature). For highly charged ions in an EBIT, charge exchange (CX) recombination is significant despite the relatively low density of neutral ions. Uncertainties of the CX cross sections combined with the limited knowledge of the experimental parameters (neutral density, relative ion velocity) constrain the models of spectral emission. To combine the unknown factors into one free parameter, we introduce a charge exchange factor that can be accurately determined experimentally using measured line intensity ratios and theoretical cross sections. Using measured Fe spectra at multiple electron beam energies (9.21 kV x 18 kV), the charge exchange factor was determined in a measurement at NIST. The factor was used in our collisional-radiative (CR) model* to produce simulated spectra and line intensity ratios. The agreement demonstrates the usefulness of this approach for spectral modeling.