Research Project
9563043
Project Summary/Abstract X-ray microscopy systems with resolution in the tens of nanometers are enabling significant advances in studies of cellular structure and function, protein crystallography and many other fields. The reliance on synchrotron sources of x-ray flux, however, limits the scope of the work that can be done and the access many groups have to this powerful tool. As of 2014, for example, there were only four cryo-SXT microscopes installed and operational at synchrotrons worldwide. Alternative sources such as liquid metal jet (LMJ) and miniature synchrotrons are advancing but still have limited brightness, for long image acquisition times, and they too require rotation of the subject for tomographic imaging. The proposed wave-guided x-ray tomographic microscope (WXTM) will combine recent advances in wafer- based x-ray waveguides developed at the University of Gottingen, now used with synchrotrons, with a novel electron beam impact source called the forward flux channel (FFC) developed at Stellarray. A tapering optic will connect these two components for efficient coupling of exit beams to the acceptance angles of the waveguide input. In the FFC primary source, x-rays are generated by e-beams accelerated into holes or slits in a metal anode target, for a kind of 3-D anode geometry that will produce an extended source of sheet beam flux. This is ideally suited to coupling to a long line of entrances to high aspect-ratio waveguide channels that will be combined to exit a 50 nm or smaller exit at the other end of the waveguide. FFC sources efficiently use nearly all the e-beam, supplied by lateral cold cathode edge emitters, and spread the beam over a very large anode surface area so high power can be input to the source. Wafer-based waveguides have been developed at Gottingen that can transmit up to 40% of the flux input and compress the beams to high orders. The specific aims of Phase I are to conduct detailed parametric studies of the primary source, optical coupling and waveguide combining branch patterns for an initial source design, and de-risk the major new components ? the FFC and the waveguide chip ? by process development, fabrication and test. Phase II will build on this work to make the full x-ray source and a prototype 2-D projection microscope with at least an order of magnitude higher flux intensity and brightness than LMJ sources, to approximate second generation synchrotrons. The WXTM source will be small and light enough for rotating or stationary tomography systems with no subject rotation, or for phase contrast, building on the Phase II platform. The target energy for the project will be 8 keV using Cu anodes, but other sources can be developed for the water window or for harder beam imaging. The outcome of the project will be a versatile new x-ray microscopy tool that will make this imaging modality widely accessible to research groups and commercial customers. WXTM will be the workstation to the synchrotron supercomputer ? lagging behind, but spreading the benefits x-ray microscopy more widely and into new areas.
