X-ray tube structure

X-ray tubes provide the primary X-rays beam by which the sample is excited to fluorescence. Fine focus X-ray tubes with a fixed anode are generally used for TXRF. An X-ray tube consist of a spiral filament acting as the cathode and a water cooled block of copper as the anode.

Both electrodes are sealed off in an evacuated glass-(ceramic)-metal cylinder.

The filament made out of Tungsten wire is embedded in a narrow steel groove (1 mm x 10 mm).

The copper block is platted with the actual tube anode material. Molybdenum is probably the most widely used anode material for TXRF.