International Collaborations on High Energy Density Matter

High energy density matter is an exciting research field as it combines fundamental, astrophysical and energy research. The creation of such matter in the laboratory is very difficult as it is under enormous pressure after large amounts of energy are deposited (usually above 1 Megabar or 1 million times the pressure of our atmosphere). However, such large pressures naturally exist in the interior of giant planets (e.g., Jupiter, Saturn and many planets outside our solar system) and inside stars. Thus, enhancing our knowledge in high energy density physics increases our understanding of the universe and its development. The most exciting technical application that needs high energy density physics is energy production by means of inertial fusion energy. One way to make the energy source of the stars applicable for energy production is to compress the fuel 1000 times while heating it to over 10 million degrees. This approach is currently tested at the National Ignition Facility in Livermore, USA. When successful, this new energy source can revolutionise our modern world, but the first success as well as further optimisation will require an improved understanding of high energy density matter.The present project will address these problems in three ways: Firstly, the applicant will participate in an experiment on high energy density matter which uses the brand-new x-ray laser LCLS in Stanford, USA. Here, we (a large, UK-led international collaboration) will test the melting and further heating of carbon under ultra-fast energy deposition. Secondly, it combines the theoretical work done at Warwick with the expertise of the experimental team in Livermore. Here, the question of how such exotic states of matter can be diagnosed in the laboratory will be discussed. Thirdly, current issues in fusion research (especially heat transport and distribution) will be addressed. The applicant and the simulation group in Livermore will discuss how new models developed in Warwick can be implemented in the large computer models that are needed to simulate real fusion experiments. This can lay the ground for a very important UK-US connection on energy research.

The largest possible impact on society will occur when fusion becomes applicable for energy production. Eventually, fusion will provide a clean, relatively cheap and carbon-free energy source that is urgently required by the rising industrial and private demand world-wide. Of course, this small project will not provide this energy source by itself. However, it is connected to one of the main research projects that aims at this grand challenge as experiments testing high energy density matter are designed to address specific problems in fusion research. Indeed, all parts of the project are connected to fusion research: the melting of carbon is an essential property needed for the smooth compression of the fuel (present experiments actually used high-density carbon as ablator). To obtain ignition and later for optimisation, fusion experiments require the best diagnostics possible. Developing x-ray scattering as a probe of dense matter will thus directly contribute. Last but not least, providing the best models for kinetic properties of the compressed fuel to the simulation groups in Livermore will have a direct impact. This project will provide the basis for this connection. As a result, it will enhance the competitiveness and standing of the UK fusion community. It will also help to better link UK research activities to the largest (and most expensive) fusion experiment presently in operation. The connection to the experimental programmes led by UK groups will underpin the support and funding EPSRC provides for these groups. It is particular important that we demonstrate our abilities and run a successful experiment at LCLS, a new x-ray laser facility unique in the world. Future applications for beam time will depend on our first results as this machine is heavily oversubscribed and, thus, any application must be very competitive. Direct theory support provided by this proposal is here essential for the success. The collaborations established and the knowledge obtained will also influence the programmes in the UK, e.g., using lasers at the Central laser facility of the Rutherford Appleton Laboratory or at the ORION laser presently build at AWE plc. The applicant has well-established links to both programmes; the connection to RAL is documented in a number of high-level publications, the latter is ensured through supervision of a PhD student working at AWE.