X-Ray Free Electron Lasers

The X-ray generation in an XFEL undulator. Picture Credit : European XFEL

One of the key challenges faced in laser plasma experiments lies in probing the highly transient, complex states generated. A laser plasma experiment is typically considered ‘long’ if states can be maintained for a billionth of a second, with many experiments being a further 1000 times faster. In this limited time we aim to study gross properties (such as density and temperature) as well as more nuanced properties, such as the structure of the material, or the properties of collective modes, such as plasma waves.

X-ray Free Electron Lasers (XFELs) are the brightest X-ray sources on the planet (a billion times brighter than any synchrotron). With pulse lengths of below 10-13 s they are able to resolve rapid dynamics. Furthermore, the X-rays are monochromatic, tuneable in energy, fully spatially coherent and have low divergence. All of this makes them ideally suited to studying matter ranging from nanostructured solids, solid and liquid material compressed to planetary core conditions, or even the generation and probing of warm dense matter or plasma systems.

As a relatively new, and highly disruptive technology, XFELs promise to continue opening and enabling new avenues of scientific exploration. Find out more.

References

D. Milathianaki et al “Femtosecond Visualization of Lattice Dynamics in Shock-Compressed Matter”, Science 342, Issue 6155, pp. 220-223 (2013)

C. Wehrenberg et al. “In situ X-ray diffraction measurement of shock-wave-driven twinning and lattice dynamics” Nature 550, 496–499 (2017)

A Schropp et al. “Imaging Shock Waves in Diamond with Both High Temporal and Spatial Resolution at an XFEL”, Scientific Reports, 5, 11089 (2015)

S. M. Vinko et al. “Creation and diagnosis of a solid-density plasma with an X-ray free-electron laser”, Nature 482, 59–62 (2012)

J. N. Clark et al. “Ultrafast Three-Dimensional Imaging of Lattice Dynamics in Individual Gold Nanocrystals”, Science,341, Issue 6141, pp. 56-59 (2013)