Some Characteristics of the Hollow Cathode Discharge Source from Hollow Cathodes of Different Sizes and Shapes

The empirical evaluation of several types of two-piece hollow cathodes for the analysis of microsamples using both dc and pulsed discharge modes of the hollow cathode discharge is reported. The discharge parameters used are similar to those that have given good precision and sensitivity for microsamples in this laboratory. Both optical microscopy and scanning electron microscopy were used to follow sputtering effects on the cathode geometry. The sputtering patterns in the flat-bottom, two-piece cylindrical hollow cathode revealed directly the cathode dark space on the cathode cavity bottom. The temporal emission profiles from the spherical cathode cavity are similar to those observed in cylindrical cathode cavities. The temporal emission profile changes with the diameter of the cylindrical cathode cavity and is characteristic of the analyte.