Hybrid Seminar hosted on-slide at SLAC in 053 Trinity Conference Room and over Zoom.
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Speaker: Henning Friis Poulsen, DTU
Program Description
In this talk I will first present the status on two diffraction based synchrotron imaging methods, 3DXRD and DFXM. These allow acquiring 3D movies of grains, domains and defects in mm sized crystalline specimens and the associated evolution of local strain. I will present kinematical scattering and wavefield propagation methods enabling direct interfacing of such data with 3D multiscale micro-mechanical and phase field models. I will comment on contrast mechanisms, current limitations and perspectives for coupling with coherence based methods for improved spatial resolution.
In a collaboration with LLNL, Stanford and SLAC we recently demonstrated the visualization of acoustic waves propagating in diamond by means of a pump-probe scheme at LCLS. The S/N of each pulse is sufficient to provide good contrast. Next I will present a science case for direct visualisation with DFXM of stochastic and irreversible phenomena such as nucleation events, dislocation movements and phase transformations, on the µs time level.
Biography
Henning Friis Poulsen is a professor at the Physics Department of the Technical University of Denmark. His research interest is at the crossroad between x-ray and neutron physics, crystallography and multiscale materials science (metals, energy materials). Specifically, he has developed hard X-ray microscopy as an in situ approach for filming the evolution of the internal structure of hierarchical materials and applied this for studies of plasticity, coarsening and flow. He is the recipient of two ERC Advanced Grants, the head of the 3D Imaging Center in Denmark, and involved with instrumentation at ESRF, ESS and MAX IV. Moreover, he is co-founder of three companies.
