Structure factors in warm dense matter
Lead Research Organisation:
Queen's University Belfast
Department Name: Sch of Mathematics and Physics
Abstract
In this research we intend to explore the properties of matter under conditions of high density at temperatures of about 5,000-100,000K. These conditions are relevant to the interiors of planets and understanding more about the microscopic structure and other properties of such matter will help in understanding the structure and formation of planets.
We will conduct the research, principally, by using high power lasers to create such "warm dense matter" conditions by driving shock waves of millions of atmospheres pressure into sample foils. We will probe the material using intense short pulses of X-rays. By observing the distribution of scattered X-rays we will be able to infer the short range arrangements of the ions in the sample and thus infer information about the ion-ion potential. By extracting this information, we would, in principle, be able to extract further information about the bulk properties such as electrical and thermal conductivities and compressibility.
We will conduct the research, principally, by using high power lasers to create such "warm dense matter" conditions by driving shock waves of millions of atmospheres pressure into sample foils. We will probe the material using intense short pulses of X-rays. By observing the distribution of scattered X-rays we will be able to infer the short range arrangements of the ions in the sample and thus infer information about the ion-ion potential. By extracting this information, we would, in principle, be able to extract further information about the bulk properties such as electrical and thermal conductivities and compressibility.
Planned Impact
The work proposed in this project is, by its nature, academic science and thus connection to potential economic impact is remote at present. Concerning the general public outside of the scientific community the possible longer term impact is as follows:
A perusal of news stories and television documentaries will reveal that there is a huge public appetite for science related to astronomy. Indeed, there is a very active amateur astronomy community; The Sky at Night is one of the longest running TV shows in the world.
Our work on the structure of warm dense matter is very closely related to the planetary and astrophysical sciences. An understanding of warm dense matter - be it water, hydrogen, ices or heavier materials such as iron, is essential to the understanding of planetary structure and crucially their formation. There are currently hundreds of known exo-solar planets. These are mostly large planets, probably gas giants. A better undertsanding of planetary formation and structure may help improve estimates of the number that may be Earth-like and understanding warm dense matter is a part of this process. Thus, we assert that our work is closely related to science that the public has an interest in. Such public interest is in turn good for science generally. The TARANIS laser, which forms a key part of the research programme is itself a significant part of our outreach programme in that, on open days, UCAS days and other events where young people visit our department, it is a key stop-off point on the tour of the department. It has hosted young researchers on summer internships and is well integrated into our 4th year MSci undergraduate projects programme.
Concerning the academic community we shall seek to make an impact in the following ways. We shall attend conferences with specific audiences in mind. For example, we have sought funds to attend the Radiative Properties of Hot Dense Matter conferences. These are held every 18 months and are small (100 delegates) meetings of specialists in our field. These are the people most likely to cite our work and getting them to see our results first hand will raise the citation profile of our EPSRC funded work and help encourage leading scientists to consider collaborative efforts with us.
In recent years, we have been successful in generating such collaborations. We have carried out experiments at Osaka, LULI, LLNL and FLASH as well as VULCAN. These are collaborations with The University of Oxford, Stanford University, Lawrence Livermore Laboratory, Technical University of Darmstadt, DESY, Ecole Polytechnique, ILE Osaka and others. These have led to publications in Physical Review Letters and Nature Physics. Application for beam time on all these facilities is open to us and forms part of our work plan.
We will also attend the European Physical Society conferences. These are much larger (700 delegates) meetings of researchers from all branches of plasma physics. This will help raise the profile of our sub-field of warm dense matter within the plasma community generally. Finally, we will attend national meetings (IOP Plasma Physics Conference). This is a national meeting of the plasma community and will allow us to disseminate our work to colleagues who may have input into national priorities in funding and facilities.
A perusal of news stories and television documentaries will reveal that there is a huge public appetite for science related to astronomy. Indeed, there is a very active amateur astronomy community; The Sky at Night is one of the longest running TV shows in the world.
Our work on the structure of warm dense matter is very closely related to the planetary and astrophysical sciences. An understanding of warm dense matter - be it water, hydrogen, ices or heavier materials such as iron, is essential to the understanding of planetary structure and crucially their formation. There are currently hundreds of known exo-solar planets. These are mostly large planets, probably gas giants. A better undertsanding of planetary formation and structure may help improve estimates of the number that may be Earth-like and understanding warm dense matter is a part of this process. Thus, we assert that our work is closely related to science that the public has an interest in. Such public interest is in turn good for science generally. The TARANIS laser, which forms a key part of the research programme is itself a significant part of our outreach programme in that, on open days, UCAS days and other events where young people visit our department, it is a key stop-off point on the tour of the department. It has hosted young researchers on summer internships and is well integrated into our 4th year MSci undergraduate projects programme.
Concerning the academic community we shall seek to make an impact in the following ways. We shall attend conferences with specific audiences in mind. For example, we have sought funds to attend the Radiative Properties of Hot Dense Matter conferences. These are held every 18 months and are small (100 delegates) meetings of specialists in our field. These are the people most likely to cite our work and getting them to see our results first hand will raise the citation profile of our EPSRC funded work and help encourage leading scientists to consider collaborative efforts with us.
In recent years, we have been successful in generating such collaborations. We have carried out experiments at Osaka, LULI, LLNL and FLASH as well as VULCAN. These are collaborations with The University of Oxford, Stanford University, Lawrence Livermore Laboratory, Technical University of Darmstadt, DESY, Ecole Polytechnique, ILE Osaka and others. These have led to publications in Physical Review Letters and Nature Physics. Application for beam time on all these facilities is open to us and forms part of our work plan.
We will also attend the European Physical Society conferences. These are much larger (700 delegates) meetings of researchers from all branches of plasma physics. This will help raise the profile of our sub-field of warm dense matter within the plasma community generally. Finally, we will attend national meetings (IOP Plasma Physics Conference). This is a national meeting of the plasma community and will allow us to disseminate our work to colleagues who may have input into national priorities in funding and facilities.
Organisations
Publications
Helfrich J
(2015)
Investigation of the solid-liquid phase transition of carbon at 150 GPa with spectrally resolved X-ray scattering
in High Energy Density Physics
White S
(2013)
X-ray scattering from warm dense iron
in High Energy Density Physics
Mabey P
(2015)
Characterization of x-ray lens for use in probing high energy density states of matter
in Journal of Instrumentation
Brozas F
(2018)
Using a commercial mini-X-ray source for calibrating Bragg crystals
in Journal of Instrumentation
Booth N
(2015)
Laboratory measurements of resistivity in warm dense plasmas relevant to the microphysics of brown dwarfs.
in Nature communications
White S
(2020)
Time-dependent effects in melting and phase change for laser-shocked iron
in Physical Review Research
Kraus D
(2015)
The complex ion structure of warm dense carbon measured by spectrally resolved x-ray scatteringa)
in Physics of Plasmas
Riley D
(2018)
Generation and characterisation of warm dense matter with intense lasers
in Plasma Physics and Controlled Fusion
Denoeud A
(2016)
Dynamic X-ray diffraction observation of shocked solid iron up to 170 GPa.
in Proceedings of the National Academy of Sciences of the United States of America
Brown CR
(2014)
Evidence for a glassy state in strongly driven carbon.
in Scientific reports
| Description | In this award we found strong coupling effects on the scattering angular cross section for Al and we also measured cross sections for Fe. This showed a steeper than expected rise with angle. During this award we carried out experiments on the LCLS free electron laser that showed significant time dependent effects that can be attributed to super-heating effects. |
| Exploitation Route | Further work on superheating is of great interest to the WDM community who rely on assumptions about timescales that may not be valid. |
| Sectors | Education,Other |
| Description | There are two main strands to the outcomes from this research project, both are relevant to the further understanding of matter in extreme conditions, relevant to planetary interiors and inertial fusion experiments. The first strand was to investigate the behaviour of shock compressed matter, in particular aluminium and iron. Iron was of particular interest because it is relevant to planets such as Earth, where the core is believed to be primarily iron under pressure of millions of atmospheres and temperatures of thousands of degrees. Typically, experiments in the field use high power lasers to generate shocks in this pressure and temperature range. However, the timescale for these experiments is in billionths of a second (nanoseconds). Our work illustrated quite clearly that timescale effects can have a key influence on the results. Our data in White et al (2020) showed, for the first time, direct measurement of a crystalline structure for iron under shock compressions where we would have expected melting to a liquid state to have been induced by the shock. This has significance since the equations that link pressure density and temperature in simulations of these extreme states of matter (so called "equations of state") are usually written for equilibrium cases where phase changes are accounted for at expected phase change boundaries for static compression and these may not be valid in some cases. The second strand relates to the understanding of XUV absorption in so called warm-dense aluminium (solid density at about 10,000 degrees). This problem has presented a significant test of modelling of such matter and experiments are key in deciding amongst competing theoretical approaches. Our most recent paper (Hyland et al 2021) showed a clearly better agreement with the calculations of Iglesias and Hollebon over those of Shaffer. |
| Sector | Education,Other |
| Impact Types | Cultural,Societal |