Improved axial plane distance and velocity determination for ultrafast electron beam X-ray computed tomography

Ultrafast electron beam x-ray computed tomography (UFXCT) has in recent years become an indispensable tool for multiphase flow studies. An essential feature of this technique is fast cross-sectional imaging in two distinct planes. Both the spatial location of focal spot path and detectors as well as the angular scanning range in UFXCT differ from that of conventional x-ray CT systems. This brings in a spatial dependence in axial scanning position and resolution. In this paper, we present an analysis of this problem, which results in an improved description of the location and shape of the imaging regions, a more accurate map of the distance between the imaging planes and, finally, a higher precision in the determination of axial structure velocities. The benefit of this improved approach is exemplarily demonstrated for a two-phase pipe flow around an obstacle.