Development and characterization of a novel compact x-ray source

Abstract

For elemental analysis, x-ray fluorescence spectroscopy (XRF) is a rapid and simple method of analysis, which provides both quantitative and qualitative information. In general, most XRF instruments are not suited for use as portable field instruments. Most commercial XRF spectrometers require cooling units for the anode, large power supplies and, in some cases, liquid nitrogen to cool the x-ray detectors. Alternative x-ray sources using radioactive isotopes have been considered for portable XRF, but safety regulations and public concerns have hampered their usage. An x-ray source has been developed which uses a solid state electron multiplier to enhance the electron gain from a simple filament. The overall gain from the electron multiplier is sufficient to generate x-rays. However, the novel source produces less heating of the anode, eliminating the cooling unit requirement. This feature along with the small size of the electron multiplier, allows for a compact design, which lends itself to portability. An additional feature is that the power consumption of the system is lower than a typical xray tube system. Initial studies have shown that the system behaves similar to a conventional x-ray tube. Increasing anode voltage (electron energy) causes improved yield of the higher energy x-rays. Also, increasing the electron multiplier voltage (electron intensity) increases overall intensity of the x-ray output. Using the new source for XRF studies, the limits of detection were comparable with values reported in the literature. It was necessary, however, to prepare the samples using single elements to reduce matrix affects and lessen effects of overlapping peaks. In general the x-ray source shows potential as a portable x-ray source that may be used in the field.