Background Low-energy X-ray spectra are essential for the characterization of light elements in X-ray fluorescence (XRF) analysis and other related measurement techniques. To minimize the absorption of low-energy X-rays and improve their utilization efficiency, low-atomic-number materials are typically employed as X-ray transmission windows, among which beryllium (Be) foil is the most widely used.

Purpose This paper aims to develop an X-ray tube equipped with an ultra-thin beryllium window with a thickness of 30 μm, and investigate its performance including X-ray transmission characteristics, spectral features and operational reliability.

Methods A sealed-off 100 kV X-ray tube with a 30 μm ultra-thin beryllium window was designed, fabricated and experimentally tested. X-ray transmittance, focal spot and beam current were analyzed via numerical simulation. Vacuum brazing and vacuum baking processes were adopted to ensure the welding tightness of the beryllium window and long-term vacuum stability inside the tube. Prototyped X-ray tubes were tested in terms of focal spot, beam current and energy spectrum, and an 8-hour continuous operation experiment was carried out to evaluate the long-term operational reliability of the X-ray tube.

Results A 100 kV X-ray tube with a 30 μm ultra-thin beryllium window was successfully developed. Simulation results show that for soft X-rays in the energy range of 1–5 keV, the transmittance of the 30 μm beryllium window is approximately 67% higher than that of a conventional 200 μm beryllium window. Performance tests indicate that the X-ray tube achieves a tube current of 1 mA and an output power of 100 W at a filament operating current of 2.07 A, with a focal spot size of 0.74 mm × 0.83 mm. The obtained X-ray spectrum presents typical continuous bremsstrahlung radiation together with characteristic X-ray lines of the tungsten target. The 8-hour long-term reliability test demonstrates that the ultra-thin beryllium window X-ray tube operates steadily without failure, arcing or overcurrent, and the tube current remains stable during continuous operation.

Conclusions The X-ray tube with a 30 μm ultra-thin beryllium window remarkably optimizes the transmission performance of soft X-rays. Comprehensive performance indicators, including filament current, focal spot size and spectral characteristics, satisfy the application requirements of fluorescence analysis under high-power and high-voltage operating conditions. No performance degradation is observed after the experiment, verifying excellent long-term operational stability and reliability of the device.