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Abstract Electron beam ion traps (EBITs) are compact devices optimized for producing ions in high charge states for spectroscopic studies or as extracted beams. Key characteristics, such as current density and electron-ion overlap, govern ionization and excitation rates. Using visible and X-ray imaging of emissions from highly charged ions, the spatial distributions of the electron beam and ion cloud in the Smithsonian Astrophysical Observatory (SAO) EBIT were measured, enabling the determination of the effective electron density. The nominal electron beam full width at half maximum (FWHM) was determined to be 92.0 ± 9.7 μm, while the ion cloud FWHM was 410.5 ± 16.5 μm, indicating an effective electron density roughly an order of magnitude lower than determined geometrically. The effects of magnetic fields on the electron beam size were also investigated, demonstrating sensitivity to the focusing magnet and bucking coil currents. These findings emphasize the need for simultaneous measurement of the effective electron density to improve the accuracy of density-sensitive studies in EBIT systems. 

Abstract In this report we describe the design and operation of the electron beam ion trap (EBIT) at the Smithsonian Astrophysical Observatory (SAO). We also provide an overview of recent upgrades that have led to improved system stability and greater user control, increasing the scope of possible experiments. Observations of X-ray emission from background elements were made after the system upgrades. The evolution of the spectrum, produced at beam energies ranging from 1285 eV to 3095 eV, allowed us to identify emission from multiple charge states and from key processes, such as dielectronic recombination, in Ba and Si ions. Emission from these background elements was easily removed by periodically dumping the trap every 2 s or less. 

Abstract We report the detection of the [Oiii] auroral line in 42 galaxies within the redshift range of 3 <z< 10. These galaxies were selected from publicly available JWST data releases, including the JADES and PRIMAL surveys, and observed using both the low-resolution PRISM/CLEAR configuration and medium-resolution gratings. The measured electron temperatures in the high-ionization regions of these galaxies range fromT_e([Oiii]) = 12,000 to 24,000 K, consistent with temperatures observed in local metal-poor galaxies and previous JWST studies. In 10 galaxies, we also detect the [Oii] auroral line, allowing us to determine electron temperatures in the low-ionization regions, which range betweenT_e([Oii]) = 10,830 and 20,000 K. The directT_e-based metallicities of our sample span from 12 + log(O/H) = 7.2 to 8.4, indicating these high-redshift galaxies are relatively metal-poor. By combining our sample with 25 galaxies from the literature, we expand the data set to a total of 67 galaxies within 3 <z< 10, effectively more than doubling the previous sample size for directT_e-based metallicity studies. This larger data set allows us to derive empirical metallicity calibration relations based exclusively on high-redshift galaxies, using six key line ratios: R3, R2, R23, Ne3O2, O32, and O3N2. Notably, we derive a novel metallicity calibration relation for the first time using high-redshiftT_e-based metallicities: $\hat{R}$= 0.18log R2 + 0.98log R3. This new calibration significantly reduces the scatter in high-redshift galaxies compared to the $\hat{R}$relation previously calibrated for low-redshift galaxies.