Metrology of steel micronozzles using x-ray propagation-based phase-enhanced microimaging

With high-energy and high-brilliance x-rays available at third-generation synchrotron sources, propagation-based phase-enhanced imaging was developed as a unique metrology technique to visualize the internal structure of high-pressure fuel-injection micronozzles. We have visualized the micrometer-scale machining and finishing defects inside a 200-μm-fuel-injection micronozzle in a 3-mm-thick steel housing using phase-enhanced x-ray imaging. Because of the phase enhancement, this new microimaging-based metrology technique has paved the way to directly study highly transient fluid dynamics in the micronozzles in situ and in real time, which is virtually impossible by any other means.