Simulations of Wolter Optics Tomography of a Fuel Cell

Abstract

Wolter optics present the opportunity to realize a practical neutron lens, which would convert a neutron imaging instrument from a pinhole camera to a microscope. This conversion would result in significant increases in neutron flux (up to 10,000 gain over the pinhole geometry) while maintaining high spatial resolution (about 3 μm). The Wolter optic system is currently being fabricated, and the first mirrors are expected to arrive in SEP 2023. As such, we focus this presentation on image simulation efforts. A ray tracing code has been developed that is able to simulate full three-dimensional imaging of extended objects placed in the Wolter optics neutron microscope. To simulate a fuel cell, we employ tomography measurements based on X-ray tomography and CAD-model derived volumes. The reason the Wolter optics system realizes such a large gain in flux is by focusing much of the flux from an extended neutron guide onto a small spot. Thus, conventional radiography of an extended object will not be possible, as the beam is similar to a cone beam which emanates from a small spot. We derive a tomography algorithm for this spot and will show its effectiveness on reconstructing simulated images. We also report on expected performance of the fabricated optical system in the current instrument configuration. Figure 1