Initial swept performance assessment of the BHx streak tube (invited)

The BHx streak tube was designed to be capable of sub-picosecond temporal resolution and high spatial resolution across a flat 25 mm photocathode, with internal photoelectron throughput several times greater than comparable deployed units. A prototype was built and evaluated for static focusing performance using a UV laser source [Raymond et al., Rev. Sci. Instrum. 96, 103503 (2025)], showing good agreement with simulation predictions. Here, we present initial swept UV measurements at an intermediate sweep speed of 260 V/ns, yielding a record length of 1.6 ns with measured time resolution of 4.2 ps across the sweep-evidently limited by the current detector assembly. Using a ps-scale laser system, the measured temporal resolution is shown to be consistent with model predictions once the detector contribution is incorporated. We describe the modeling framework, performance predictions, time-base calibration method, and the comparison between measured and predicted results. We also outline the path to operation at full sweep speed and discuss future adaptation to x-ray sources.