Laser-wakefield accelerators for high-resolution X-ray imaging of complex microstructures

Hussein, A.E. and Senabulya, N. and Ma, Y. and Streeter, M.J.V. and Kettle, B. and Dann, S.J.D. and Albert, F. and Bourgeois, N. and Cipiccia, S. and Cole, J.M. and Finlay, O. and Gerstmayr, E. and González, I.G. and Higginbotham, A. and Jaroszynski, D.A. and Falk, K. and Krushelnick, K. and Lemos, N. and Lopes, N.C. and Lumsdon, C. and Lundh, O. and Mangles, S.P.D. and Najmudin, Z. and Rajeev, P.P. and Schlepütz, C.M. and Shahzad, M. and Smid, M. and Spesyvtsev, R. and Symes, D.R. and Vieux, G. and Willingale, L. and Wood, J.C. and Shahani, A.J. and Thomas, A.G.R. (2019) Laser-wakefield accelerators for high-resolution X-ray imaging of complex microstructures. Scientific Reports, 9 (1): 3249. ISSN 2045-2322

Abstract

Laser-wakefield accelerators (LWFAs) are high acceleration-gradient plasma-based particle accelerators capable of producing ultra-relativistic electron beams. Within the strong focusing fields of the wakefield, accelerated electrons undergo betatron oscillations, emitting a bright pulse of X-rays with a micrometer-scale source size that may be used for imaging applications. Non-destructive X-ray phase contrast imaging and tomography of heterogeneous materials can provide insight into their processing, structure, and performance. To demonstrate the imaging capability of X-rays from an LWFA we have examined an irregular eutectic in the aluminum-silicon (Al-Si) system. The lamellar spacing of the Al-Si eutectic microstructure is on the order of a few micrometers, thus requiring high spatial resolution. We present comparisons between the sharpness and spatial resolution in phase contrast images of this eutectic alloy obtained via X-ray phase contrast imaging at the Swiss Light Source (SLS) synchrotron and X-ray projection microscopy via an LWFA source. An upper bound on the resolving power of 2.7 ± 0.3 μm of the LWFA source in this experiment was measured. These results indicate that betatron X-rays from laser wakefield acceleration can provide an alternative to conventional synchrotron sources for high resolution imaging of eutectics and, more broadly, complex microstructures. © 2019, The Author(s).