Interview with Prof. Justin Wark, University of Oxford

I had the delightful opportunity to conduct my doctoral research work under some of the most distinguished scientists in the work while at Oxford. My suprvisors were Dr. Gianluca Gregori, Prof. Andrew Jephocoat and Prof. Justin Wark. Justin has had long-lasting relations with Czech science and has covered a very wide range of research and I am happy to intorduce an interview with him in my next blog.

Justin Wark is a Professor of Physics at the University of Oxford and fellow of Trinity College, Oxford. He is the leader of a research group focusing on the ultra-high power optical and x-ray lasers to generate and diagnose extreme states of matter, at high temperatures, pressures and densities falling to the regimes of warm dense matter and shocked solids. He pioneered many aspects of shock physics, laboratory astrophysics, atomic physics and plasma physics. He has carried out remarkable work as one of the first users and promoters of the x-ray free electron lasers as a tool in high energy density physics and has conducted many successful experiments at DESY in Hamburg and LCLS, Standford University in the USA. He is a graduate from the Oxford Physics department and received his PhD in Plasma Physics at Imperial College London in 1985. He spent some time as a researcher at the Laboratory for Laser Energetics, University of Rochester, USA, before returning to England in 1988 to take up a faculty position at Oxford. Here he set up the High Power Laser Research Group.

Prof. Justin Wark

You had a long and very successful scientific career which actually started while you were studying in Oxford, afterwhich you continued to the Imperial College and USA. What brought you back?

The time I spent in the US -  as a postdoctoral fellow at the Laboratory for Laser Energetics at the University of Rochester, was a very formative time for me.  It was an exceptional privilege to work  in such an impressive scientific environment, and one which was so well organised, and fully focussed on doing high quality science and presenting it well.  Indeed, sometimes on looking back I think that the most important thing I learnt in Rochester was how to present work in a clear and concise way.  Given the science facilities were superb, and the prospects good, why did I return to the UK, and specifically Oxford?  That's a good question!  I suppose that the answer, as for many who return to their home country, is much more to do with personal reasons than rational thinking about career prospects.  Although I enjoyed living in the US, and now love being able to visit frequently, after two years as a postdoc I had a strong desire to live in a place and culture I called home, and knew that if I did not return at that point, I never would.  I therefore decided that the best thing to do was to return to the UK, and see if I could carve out a scientific career there.  Perhaps a little arrogantly, I had in the back of my mind that I could always return to the US if it didn't work out!    Oxford appealed to me strongly as I was there as an undergraduate, and I knew its dedication to high quality teaching as well as research, and also for me Oxford has always been much more than simply a good Physics department - it has the feel of a true University in the sense that it is a republic of scholars, and there are strong links across faculties and departments, and the College environment automatically pushes you into contact with people from a wide variety of disciplines -  those are the things that appealed (and still appeal) to me.

Would you give us some highlights of your current work?

In my view the present time is a most exciting period for my field of high energy density science.  We have two different exquisite, revolutionary, and complementary facilities at our disposal: the LCLS X-ray laser at SLAC, and the National Ignition Facility at LLNL.   These are both truly remarkable machines.  LCLS is a source of X-rays with a spectral brightness a billion times greater than any other source on the planet, and being one of the first users of that machine has been one of the highlights of my career.  We recently published in Nature the results of our first experiment, where we demonstrate heating a solid to temperatures in excess of 2 million Kelvin so rapidly (within 80 fsec) that no expansion took place, so we could really study the dense plasma under well controlled conditions.  This has led us to a much better understanding of the fundamental physics of dense plasmas, in particular how their ionization potential is influenced by their environment.  Turning to the NIF - the US is opening up this facility to academic users, and my group has been fortunate enough to gain access, and we are planning experiments aimed at performing X-ray diffraction on solid matter at pressures far above those present at the centre of the earth, and way in excess of those achievable with diamond anvil cells.  We are hoping this will open up a whole new branch of high pressure physics. 

How is teaching at Oxford?

Teaching at Oxford is hard work, time-consuming, but incredibly rewarding.  Oxford is renowned for its tutorial system, where the academics mentor very small groups of students through pretty much all the physics course.  For the tutors this means we get to know the students very well, but we have to teach a wide variety of subjects.  For example this last year I have taught quantum physics, atomic physics, laser physics, optics, electromagnetism, circuit theory, solid state physics etc.    Whilst that is demanding and time-consuming, it does keep us tutors on our toes!  As the groups are small, and linked into the Colleges, we build up good relationships with the students, and often keep in contact long after they leave.  Its the teaching that in many ways makes the University feel more like a community, than an institution.

How about Oxford students? The university if famous for its very selective admission process designed to ensure the best quality of students. What are the qualities Oxford university is looking for in a young individual wishing to study there at both undergraduate and postgraduate levels?

Even at undergraduate level every student is interviewed (several times) as part of the admission process -  you cannot get in simply on having high grades.  We are looking for students who have a passion and feel for the subject, and have not just learnt to repeat or parrot-back things they have gleaned from text books (important as rote learning is).  At the postgraduate level, I personally look for students who I think have or will display initiative.  So much of research is working out what the question is, as much as then finding the solution.  The best students are the ones who not only come back with a good answer to the problem that you set, but on their own have worked out several new steps, and before long they are the expert in field, rather than the supervisor.

You have had long collaborations with Czech scientstists to date. How is in your opinion Czech science percieved by the international community?

Well, I certainly don't feel qualified to speak for the international community at large!  But from my own perspective, I have had excellent and very productive interactions with colleagues from the Czech Republic.  It was not long after the fall of the Berlin Wall, and the velvet revolution that I found myself meeting scientists from the Czech Republic for the first time.  If I recall correctly, I was at a conference in Bavaria when I heard a talk by Dr Oldrich Renner, from the IOP in Prague, talking about novel X-ray spectrometers.  He put forward some fascinating ideas for extremely high resolution spectroscopy, and that chance meeting led to a long and fruitful collaborations and joint experiments, and the chance to meet and work with many more colleagues from the Czech Republic.  The impression I have gained is that there are quite a few things in common between the situation in the UK, and that experienced by Czech scientists.  In particular, neither country has the vast funding of the United States, so to compete we choose niche areas, think long and hard, and come up with novel solutions -  rather than just throw money at a problem.    In our own area of high energy density physics, and high power laser-matter interactions, Czech science has clearly punched way above its weight, and perhaps the best evidence for the high esteem in which Czech science is held in this area is that the EU have chosen Prague as one of the three main sites for the multi-million euro Extreme-Light-Infrastructure (ELI) project.

Edited by Katerina Falk