Probing matter in extremes; chemical environment in warm dense matter (plasma strand project) – accepting applications

Supervisor: Andy Higginbotham (University of York)

The field of matter in extreme conditions (one example being the warm dense states ubiquitous in inertial confinement fusion) is an exciting and expanding area of research. This so-called high energy density regime, consisting of material with pressure in excess of 1 million atmospheres, is believed to play host to matter with a range of interesting properties, including super-hard materials, high-temperature superconductors, superionic structures and electrides.

One of the challenges associated with these studies lies is effectively probing the structural and chemical properties of the material on the short timescales for which they can be maintained. For example, one route to producing HED matter is via laser compression. Suitably powerful lasers typically have pulse lengths limited to 10’s of nanoseconds, necessitating measurement with sub-nanosecond resolution. What’s more, the density of this matter is typically several times solid density, typically making the material opaque to optical light. This means that x-rays are often the probe of choice to ensure the core of the material can be adequately probed.

The past decade has seen significant advances in our ability to probe these states thanks to the emergence of facilities such as free electron lasers; ultra bright, short pulse, high flux x-ray sources. In particular, structural diagnostic such as x-ray diffraction have allowed us to gain valuable insight into material behaviour in extremis. This is, however, only part of the story.

PhD Project : In this PhD you will work to develop probes of chemical environment, such as X-ray Absorption Near Edge Structure (XANES) utilising the unique properties of x-ray FELs.  These techniques complement existing structural tools by shedding light on valency, coordination and band structure.  In particular, this important electronic information allows for a more complete understanding of material properties.  These tools are expected to have wide ranging impact, being important for the study of solids, liquids and warm dense matter across a range of conditions from planetary cores to fusion capsules.  This project is expected to involve both experimental and computational elements.

The project will be mainly based in York, but will likely involve overseas travel for conferences or collaborations, in particular to the US or Germany, for several weeks at a time.

During this project you will gain familiarity with a range of experimental x-ray techniques (including on Free Electron Lasers), simulation methodologies and programming skills in languages such as Python and/or C++.

This project is offered by University of York. For further information please contact: Andy Higginbotham (andrew.higginbotham@york.ac.uk)