Stefan Hau-Riege (15-ERD-026)
The x-ray free-electron laser can be used to control the creation of warm dense matter, a plasma state that is not very well understood, and also can be used to probe high-energy-density materials. As such, x-ray free-electron lasers, such as the Linac Coherent Light Source at the SLAC National Accelerator Laboratory in Menlo Park, can enhance our understanding of the structure and dynamics of high-energy-density matter. High-energy-density experiments on these laser systems are maturing and calling into question some long-held ideas in high-energy-density science. However, such experiments are complex to design and execute, data analysis is complicated, and there is pressure to complete experiments in one pass. We plan to develop the tools necessary for researchers to design and optimize x-ray free-electron laser high-energy-density experiments. Developing these tools will require a three-pillar approach of (1) theory, modeling, and simulations; (2) data analysis and in-line experimental support; and (3) experiments at the Linac Coherent Light Source.
For this project, we are developing and implementing an end-to-end model of experiments to facilitate design and analysis of efficient and successful high-energy-density science experimental campaigns, as well as strategies and algorithms capable of providing in-line experimental support to handle x-ray free-electron laser data streams in excess of 10 GB/s. We are also performing experiments to guide development of the simulation tool. Even though the Linac Coherent Light Source produces high-quality light, pulses are not reproducible, so we will simulate a representative number of different realizations for high-performance computing. Simulation elements include x-ray propagation, x-ray interactions with optics, sample interaction at low to high intensities, and signal generation and detection.
This project will enhance LLNL's core competencies in high-energy-density science and high-performance computing, simulation, and data science. The goal of this proposal is to enable us to effectively use x-ray free-electron lasers to develop a fundamental understanding of complex nonideal plasmas and high-pressure materials, and to help validate the models used in stockpile stewardship science and high-energy-density codes.
FY15 Accomplishments and Results
In FY15 we (1) developed a first version of the end-to-end simulation model, which allows us to calculate the wave-front incident on the sample; (2) used this model to provide support to x-ray free-electron laser high-energy-density experiments; (3) compared experimental results for the motion of high-atomic number elements in a low-atomic-number plasma with our model predictions; and (4) used our simulation capability to design a second experiment that studied the Bragg reflection from different solids to probe crystalline structure under high-intensity radiation.
Publications and Presentations
- Aquila, A., et al., "The linac coherent light source single particle imaging road map." Struct. Dyn. 2, 041701 (2015). LLNL-JRNL-669400. http://dx.doi.org/10.1063/1.4918726
- Hau-Riege, S. P., and B. Bennion, “Reproducible radiation-damage processes in proteins irradiated by intense x-ray pulses.” Phys. Rev. E. 91, 022705 (2015). LLNL-JRNL-662682. http://dx.doi.org/10.1103/PhysRevE.91.022705
- Nass, K. et al., “Indications of radiation damage in ferredoxin microcrystals using high-intensity X-FEL beams.” J. Synchrotron Radiat. 22, 225 (2015). LLNL-JRNL-663001. http://dx.doi.org/10.1107/S1600577515002349