Optimization of an electron cold cathode tube for soft X-ray spectrometry

The electron cold cathode tube for soft X-ray spectrometry was optimized. Therefore, the use of different cathode materials (aluminium, titanium and steel) was investigated with respect to the produced plasma and its discharge conditions. The current/voltage characteristics for different materials and electrode distances were measured in dependence of the operating pressure. In addition the intensities and spectral properties of the generated soft X-rays of a steel sample were compared and the sputtered surfaces of the cathodes were analysed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). It was found that aluminium cathodes yield high intensities of analytical lines, while the discharge can hardly be kept stable. Titanium cathodes produce a stable discharge over a long period of time and are very suitable for practical work.