| Several glow-discharge devices have been developed and evaluated as both emission and mass spectrometry sources for the elemental analysis of conducting and insulating solids. Research has been conducted in three areas: characterization of an rf glow-discharge emission source, magnetic-field modifications of several glow-discharge cells, and fundamental studies of the glow discharge. Two conventional sources were constructed, one viewed side-on and the other viewed end-on. The side-on-viewed source was used primarily to determine how various factors influence the plasma volume. The second glow-discharge cell was designed to optimize the collection of the analyte emission and is similar to several commercially available sources. One of the operational parameters of an rf glow-discharge source is the AC frequency. The effect of power-supply frequency on the analytical usefulness of the end-on-viewed source was explored. The rf-powered glow-discharge source was developed in order to increase the range of solids which can be analyzed, specifically it can be used to study insulating materials. A major problem with the analysis of insulators is the capacitance of the sample results in lower-density discharges. This problem can be addressed by the addition of a magnetic field to the plasma volume, which can decrease electron loss in the discharge. Both the side-on-viewed rf source and the widely used Grimm lamp (dc glow discharge) were modified with the addition of a magnetic field, with moderate improvement in the emission characteristics of both sources. A planar-magnetron glow-discharge source (the magnets are located anterior to the sample) was constructed and its physical features, emission characteristics, and mass spectrometric utility were explored. Finally, fundamental studies of the two most analytically useful sources, the end-on-viewed conventional rf source and the rf planar-magnetron source, were conducted with a single-Langmuir-probe method. The probe circuit was modified with a tuning network in order to compensate for fluctuations in the plasma caused by the oscillating rf field. The electron temperature and electron density of the plasmas were calculated from the probe data. |
