Justin Wark
Fellow and Tutor in Physics

Profile

I started my Physics career as an undergraduate at Oxford, before studying at Imperial College, London, to pursue a PhD in Plasma Physics. From there I moved to the University of Rochester in upstate New York to undertake a postdoctoral fellowship at the Laboratory for Laser Energetics. At that time in the mid-eighties, and still today, the University of Rochester has the largest laser of any academic institution in the world, and I continue to maintain close links with the facility, as well as strong collaborations with scientists at Lawrence Livermore National Laboratory in California, which hosts the largest laser in the world: the National Ignition Facility (NIF). I returned to Oxford in 1988 to set up a research group working in high power laser-matter interactions. The lasers I use are amongst the most powerful on earth: although they are only on for a brief fraction of a second, the peak power in the light is more than thirty times as powerful as the electrical output of the whole earth. Over the past few years I have also been one of the first UK researchers to use the new generation of x-ray lasers, which themselves are a billion times brighter than any other x-ray source in existence. These extraordinary machines promise to revolutionise many areas of science – the wavelength of x-rays is short enough to allow us to ‘image’ atoms, and the femtosecond duration of the x-ray pulse is shorter than the fastest vibrational periods of atoms – these two attributes allow ‘molecular movies’ to be made.

I set up the NIF User group, I am a member of the LCLS at Slac, Stanford. I have recently served on Science Board for STFC. I am a Fellow of the American Physical Society. Within the College I sit on the Bursarial Committee and Investment Committee.

Teaching

Whilst teaching a wide range of subjects across the undergraduate physics syllabus, I specialise in Atomic and Molecular Physics, Quantum Mechanics, Optics and Condensed Matter Physics. Within the Physics Department I give the lectures in the Short Option in Plasma Physics.

Research

My research interests lie in the theory, creation, and diagnosis of matter under extremes of temperature, density and pressure – conditions that are far beyond those found on earth, and only exist at the centre of the giant planets within our own solar system and beyond, or towards the centre of stars. Whilst we can never physically go to these places, it is possible to recreate similar environments in the laboratory, and to make appropriate measurements of the optical, electrical, and physical properties of such matter. Along with my research group I use the largest and most powerful optical and x-ray lasers to perform these experiments. The resulting pressures produced can be many tens of millions of atmospheres, and temperatures of millions of degrees. These ‘miniature stars and planets’ created within the laboratory have short lifetimes – sometimes only a few tens of femtoseconds, and within that brief time, all measurements must be made. Experimental data inform the fundamental theory of these dense, hot systems, and my research group also uses ab initio quantum simulations and complex atomic physics packages to model the underlying physics. Certain aspects of the work have direct relevance to the quest for laser-driven fusion energy.

Selected Publications

For an up-to-date list of my publications, please refer to my Google Scholar page:

Recent Publications in the Scientific Literature:

Density functional theory calculations of continuum lowering in strongly coupled plasmas, S. M. Vinko,O. Ciricosta, and J. S. Wark , Nature Communications, 5, 3533doi:10.1038/ncomms4533 (2014)

Femtosecond visualization of lattice dynamics in shock-compressed matter, D Milathianaki, S Boutet, GJ Williams, A Higginbotham, D Ratner, AE Gleason, M Messerschmidt, Marvin M Seibert, DC Swift, P Hering, J Robinson, WE White, JS Wark, Science, 342, 220-223, (2013)

Direct measurements of the ionization potential depression in a dense plasma, O Ciricosta, SM Vinko, H-K Chung, B-I Cho, CRD Brown, T Burian, J Chalupský, K Engelhorn, RW Falcone, C Graves, V Hájková, A Higginbotham, L Juha, J Krzywinski, HJ Lee, M Messerschmidt, CD Murphy, Y Ping, DS Rackstraw, A Scherz, W Schlotter, S Toleikis, JJ Turner, L Vysin, T Wang, B Wu, U Zastrau, D Zhu, RW Lee, P Heimann, B Nagler, JS Wark, Physical Review Letters, 109, 065002 (2012)

Creation and diagnosis of a solid-density plasma with an X-ray free-electron laser, SM Vinko, O Ciricosta, BI Cho, K Engelhorn, H-K Chung, CRD Brown, T Burian, J Chalupský, RW Falcone, C Graves, V Hajkova, A Higginbotham, L Juha, J Krzywinski, HJ Lee, M Messerschmidt, CD Murphy, Y Ping, A Scherz, W Schlotter, S Toleikis, JJ Turner, L Vysin, T Wang, B Wu, U Zastrau, D Zhu, RW Lee, PA Heimann, B Nagler, JS Wark, Nature, 482, 59-62, (2012)

Books:

Statistical Mechanics – A Survival Guide, A.M. Glazer and J.S. Wark (OUP, 2001)

Professor Wark contributes to Radio 4 Program "In Our Time", hosted by Melvyn Bragg
Professor Wark contributes to Radio 4 Program "In Our Time", hosted by Melvyn Bragg