Spectral analysis on optimizing X-ray tubes operating parameters and performance for non-destructive material quality analysis

Abstract

This Master's Thesis was made in cooperation with the University of Jyväskylä and Stresstech Oy. The purpose of this work is to compare the X-ray tubes from two different manufacturers (TruFocus and MRX), to obtain information about the properties and function of tubes and changes in spectra when measuring with different acceleration voltages and currents. The goal is to get results with which to optimize the X- ray diffraction measurements in laboratory work. For this reason, I will also briefly present the diffraction phenomenon and intensity calculations used to analyze the diffraction spectrum in some of the XRD measurements.

Measurements were carried out with tubes of three different target materials, Cr, Cu and Mn from both of the manufacturers and in addition the titanium target tube was tested from TruFocus. The acceleration voltages and currents were selected based to the top limits of each tube as well as the notations made in the laboratory work earlier.

Results were mainly as expected; the intensities of the K-alpha peaks increased with increasing voltages and currents. However, with chromium (TruFocus), the 1 kV rise in voltage in the highest range of the values no longer increased the intensity further. In a case of titanium, the bremsstrahlung radiation had significantly higher intensity maxima than the characteristic peaks which is why the exposure times need to be longer to get the signal-to-noise-ratio in acceptable level. Measurements with tubes of manganese and copper targets, and to some extent also chromium, produced unwanted effects like pile-up and secondary radiation which may distort the subsequent analysis of the measured spectra.

In general, TruFocus was more reliable and had better usability when comparing the operational function of the tubes from different manufacturers. However, the sampling in this thesis was so narrow that additional measurements are needed to confirm the observations.