Latest developments in liquid metal jet technology x-ray sources

Abstract

Since more than ten years, MetalJet sources, based on liquid-metal-jet technology, are successfully operated in many labs over the world. By using a high-speed jet of liquid metal, instead of the traditional solid- or rotating anode, it has been demonstrated that a much higher power can be applied to the anode. Since melting of the anode is thereby no longer a problem as it is already molten, MetalJet has achieved an at least 10x significantly higher brightness than the conventional solid-anode microfocus tube with the X-ray spot size range of 5- 40 µm. Key applications include X-ray diffraction and scattering, and several publications have also shown very impressive imaging results using liquid-metal-jet technology, especially in phase-contrast imaging and X-ray microscopy. The well-established way to obtain the ultimate resolution for X-ray microscopy is to use X-ray optics. Such optics normally limits the bandwidth of the spectrum, and thus requires a high brightness and relatively monochromatic X-ray source. MetalJet offer a sharp, high-intensity Kα line from Gallium emitted from a small focal spot, making a considerably larger fraction of the flux useful in the optics setup. This higher brightness makes broad applications possible also at home laboratory. Additional feature given by MetalJet is the capability of imaging copper (Cu)-rich electronics with high contrast, thanks to the usage of Gallium rich anode material. It has the K-alpha line that is slightly above the absorption edge of Cu, where a sudden drop in X-ray transmission happens and a good contrast between Cu and background elements, ex. Silicon is expected. Therefore, MetalJet source could be a good hand in imaging copper conductors of the obsolete computer chips, as well as other copper-contaminated materials in transport, construction applications. Phase-contrast imaging achieves a significant improvement on the contrast for low absorbing materials. However, it requires the X-ray source to have small emission spot (normally microfocus), high flux and stability, due to the limited lab space and/or adding of optics to retrieve the signal reliably. Therefore, the high brightness MetalJet source is a good match for doing phase-contrast imaging with compact laboratory setup, by enabling shorter exposure time, higher imaging resolution and contrast. Besides, the high stability of the source perfectly matches the requirement of the associated phase-contrast imaging techniques. Moreover, with the high brightness MetalJet source, X-ray fluorescence imaging has been transferred successfully from synchrotron to laboratory setup and its performance has reached the level of synchrotron-level. In this presentation we will go over some recent developments in the technology that bring 70 times more brightness to the lab than a solid target X-ray tube. We will also discuss some examples from the users who have used the technology to bring synchrotron application to the lab.