The ability to vary the NanoSIMS-HR source and sample high voltage from 8 keV down to 1 keV allows the user to trade off lateral resolution for depth resolution. Our results show that at 4 keV impact energy (2 keV on source, -2 keV on the sample), there is an approximately 2-fold improvement in depth resolution with an approximately 5-fold loss in lateral resolution. While the actual lateral resolution is better than it would have been with the previous thermal Cs + source, the source intensity is still affected by reducing the source high voltage because it extracts the electrons that heat the source, and the ability of the electronics to compensate has limits. We tested the P detection limit with 10 to 8000 pA Cs + primary beam current. The improvement in the detection limit with higher beam current reflects the increase in the dynamic range between the implanted P and the background . The relationship between beam current and detection limit in the P analyses in this study reflects an optimal relationship between the primary current resolution, the sputtered area and the target area for data extraction (Fig. ). We found that the optimum relationship between primary beam diameter and raster size was a factor of 20 to 30. Smaller rasters result in significant contribution of P -counts from the periphery of the analysis crater to the central ROI. We also found that the optimal ROI size is ~10% of the raster size; smaller ROIs result in a reduced dynamic range and limitation on the number of atoms in the analyzed area (Fig. ). We do not have comparable 50L data, but we would expect the ROI for any given detection limit to be larger because of the lower beam intensity. Based on previous work, the minimum size that a feature of interest could be is the size of the ROI plus two beam widths . Higher primary beam current density also lowers background for analyses such as H and O, where the background count rate is proportional to the rate at which these species in the analysis chamber vacuum interact with the sample surface . Higher spatial resolution also increases sensitivity to the composition of the target feature by sampling the feature and not the adjacent material.