Optimization of pyroelectric electron sources for the generation of x-rays for x-ray fluorescence applications

Abstract

X-ray fluorescence (XRF) spectroscopy is a frequently used technique for the chemical analysis of materials due to several advantages such as its almost nondestructive character. Subjects of this report are investigations of the pyroelectric effect with regard to its application for the generation and acceleration of x-rays and a successive usage of radiation for XRF in materials science. In order to answer questions concerning the intensity of primary radiation and of fluorescence radiation, this paper contains several experimental investigations. Different setups and measurements have been used to increase intensity. Emission behavior of electrons has been characterized using measurements of electron current in a target positioned in front of a pyroelectric crystal as a function of the temperature of the crystal and time. Radiation has been coupled out, and its dose equivalent rate has been measured. This allowed the optimization of the working pressure of the residual gas surrounding the crystal in an evacuated atmosphere (rarefied air). It has been shown that a vacuum pressure of approximately 5 × 10−1 Pa allows the generation of radiation with high intensities. Different target materials have been compared due to the intensity of excited fluorescence radiation of a sample by using an energy dispersive radiation detector. A qualitative and quantitative analysis of elements contained in the sample has been proven to be feasible. A possible application of the radiation for imaging has been investigated.