X-ray tube

An x-ray tube including

• a sealed vessel comprising a bulb having one open end and another open end, a stem fixed to the one open end of the bulb, and an output window fixed to the another open end of the bulb;
• a low voltage cathode pin and high voltage cathode pin extending through the stem, a filament for emitting electrons spanning between the low voltage cathode and the high voltage cathode in the sealed vessel;
• a focussing electrode disposed in the sealed vessel and surrounding the filament for converging electrons emitted from the filament and directing the electrons toward the output window so as to discharge an x-ray outwardly out of the output window;
• characterized by
• the focussing electrode having a lower end portion sandwiched between the bulb and the stem, and
• the stem having a surface formed with a metallized layer made from an electrically conductive material, the metallized layer extending at least from the lower end portion of the focussing electrode to the low voltage cathode pin, a brazing material being interposed between the metallized layer and the lower end portion of the focussing electrode for electrically connecting the focussing electrode to the low voltage cathode pin.