Profile

Career

Summary of expertise

• Experimental low-temperature plasma physics
• Plasma diagnostic development

Previous posts

2007-08: Research Scientist, Fraunhofer Institute for Laser Technology / Philips Extreme UV GmbH, Germany

2008-11: Postdoctoral Research Associate, University of York

Research

Overview

Research group: Plasma Physics and Fusion

Research interests:

• Experimental low-temperature plasma physics
• Plasma diagnostic development
• Plasma jets for biomedical applications
• Plasma-surface interactions for fusion research

Research profile

My main research interests are in the area of low-temperature plasma physics and diagnostic development. More specifically, developing and employing new diagnostic techniques to understand the physics behind atmospheric-pressure plasma jets for healthcare applications and plasma-surface interactions for fusion research. With this improved understanding we can further develop plasma devices for new industrial and healthcare applications.

Plasmas, or ionised gases, are all around us, not only in nature, e.g. lightning and northern lights, but also in our homes, e.g. fluorescence tubes and plasma TVs, and in many industrial production processes e.g. to make computer chips, solar cells, mobile phones, protective coatings on fabric, and many more. Plasmas exist in many different forms and they have been studied and used for applications for many decades now. Despite all these successes there are still aspects of plasmas that we don’t fully understand, and by doing research in which we are trying to understand how exactly these plasmas work, we discover exciting new applications for plasma technology. It is the combination of fundamental research, trying to work out how exactly these plasmas work, and the direct impact that this research can have on everyday life that I really like. Exciting new things that we study in our labs will lead to new and improved plasma devices which end up in new commercial products in a few years.

One of my research interests is focussed on new applications of plasmas in healthcare. The last decade has seen a strong expansion of healthcare applications of plasmas. This has been triggered by the recent development of atmospheric-pressure non-thermal plasmas. These plasmas can operate in open air, remain at room temperature, and still have the selective reactivity characteristics known from plasma processing applications. This unique combination of characteristics makes them ideal tools for healthcare. Emerging applications of low-temperature plasmas in healthcare include new sterilisation techniques for medical instruments, surgical tools for clean cutting and, very recently, development of techniques to directly treat living human tissue. These techniques have great potential and are seen by some as a revolution in medical treatment. In order to fulfil this potential and make plasmas in healthcare a success we need to develop efficient and safe plasma devices. This requires a thorough understanding and control of these plasmas and their behaviour. For this we need specialist diagnostic tools, capable of studying these small, highly transient plasmas. Laser-based spectroscopy techniques like Laser-Induced Fluorescence, Thomson Scattering, and Stark spectroscopy are all promising techniques for studying these plasmas, but need to be improved to deal with the complexity of the plasma jets. My aim is to develop and use such diagnostics such that we can create a good understanding of how these plasmas work, and how we can control and improve them, leading to commercial products. This whole process involves a multi-disciplinary team, including not only plasma physicists, but also biologists, doctors and electrical and mechanical engineers. Also, we will work together with industrial partners from a very early stage of the research to make sure that there is a direct and efficient route of transferring new ideas from academia in to industrial applications.

I am also interested in working together with colleagues within the York Plasma Institute on projects in the field of Magnetic Confinement Fusion energy, especially on plasma-surface interactions. There is a long-lasting international effort to develop fusion energy as a clean, renewable energy source for future society. An important step in that direction is the world-leading, international ITER project which is currently under construction, and is expected to prove the feasibility of fusion power in the next 10-15 years. A key issue for ITER, and fusion energy in general, is associated with plasma-surface interaction and this, in turn, has synergies with the technological plasmas discussed above. One of the main issues for ITER and future fusion power plants is the control of the interaction of the hot fusion plasma with wall materials. The wall needs to survive the enormous heat loads and particle fluxes without impacting on the fusion performance. The plasma conditions of the plasmas close to the walls of fusion devices are very different from the fully-ionised core plasmas mainly studied in fusion research. Aspects of plasma-wall interactions for fusion research can be studied accurately using low-temperature, dedicated linear plasma sources.

The temperatures (1-10 eV), densities (>10¹⁷ m^-3) and ionisation degrees (<10%) found in both fusion-edge plasmas and atmospheric-pressure plasmas used for biomedical applications are very similar. Also, for both plasmas our fundamental understanding is limited by the complexity of the plasmas in terms of different species (ions, electrons, atoms, molecules, etc.) and reaction mechanisms at play. Because of the similarities, I plan to develop sophisticated diagnostic techniques, to study the discharge behaviour relevant to both types of plasmas and employ these new diagnostics to improve the fundamental understanding of both fusion-edge plasmas and discharge behaviour of atmospheric-pressure plasma jets for healthcare applications.

Publications

Full publications list

E. Wagenaars, D.S. Whittaker, G.J. Tallents
A method to probe Rosseland and Planck mean opacities with high harmonics
High Energy Density Phys., 7, 17, 2011.

E. Wagenaars, R. Vann, M. van der Woude
Treatment of Escherichia coli with an atmospheric-pressure low-temperature plasma jet
IEEE Trans. Plasma Sci., in press, Aug 2011

D.S. Whittaker, E. Wagenaars, G.J. Tallents
Temperatures following X-ray free-electron laser heating of thin low- and medium-Z solid targets
Phys. Plasmas, 18, 013105, 2011.

N.C. Woolsey, N. Booth, R. J. Clarke, D. Doria, L. A. Gizzi, G. Gregori, P. Hakel, P. Koester, L. Labate, T. Levato, B. Li, M. Makita, R. C. Mancini, J. Pasley, P. P. Rajeev, D. Riley, A.P.L. Robinson, E. Wagenaars, J. N. Waugh
Precision x-ray spectroscopy of intense laser-plasma interactions
High Energy Density Phys., 7, 105-109, 2011

L.M.R. Gartside, G.J. Tallents, A.K. Rossall, E. Wagenaars, D.S. Whittaker, M. Kozlová, J. Nejdl, M. Sawicka, J. Polan, M. Kalal, B. Rus
Extreme ultraviolet interferometry of laser plasma material between the critical and ablation surfaces
High Energy Density Phys., 7, 91-97, 2011

N. Booth, R. J. Clarke, D. Doria, L. A. Gizzi, G. Gregori, P. Hakel, P. Koester, L. Labate, T. Levato, B. Li, M. Makita, R. C. Mancini, J. Pasley, P. P. Rajeev, D. Riley, A.P.L. Robinson, E. Wagenaars, J. N. Waugh, N. C. Woolsey
Measuring fast electron distribution functions at intensities up to 1021 W cm-2
Nucl. Instrum. Meth. A, in press, 2011

G. Tallents, E. Wagenaars, G. Pert
Lithography at EUV wavelengths
Nature Photonics, 4, 809, 2010 [commissioned News & Views article]

L.M.R. Gartside, G.J. Tallents, A.K. Rossall, E. Wagenaars, D.S. Whittaker, M. Kozlová, J. Nejdl, M. Sawicka, J. Polan, M. Kalal and B. Rus
Extreme ultraviolet interferometry of warm dense matter in laser plasmas
Opt. Lett., 35, 3820, 2010

E. Wagenaars, F. Küpper, J. Klein, W. Neff, M. Damen, P. van der Wel, D. Vaudrevange, J. Jonkers
Power scaling of an extreme ultraviolet light source for future lithography
Appl. Phys. Lett., 92, 181501, 2008

E. Wagenaars, A. Mader, K. Bergmann, J. Jonkers, W. Neff
Extreme ultraviolet plasma source for future lithography
IEEE Trans. Plasma Sci. 36, 1280, 2008

E. Wagenaars, M.D. Bowden, G.M.W. Kroesen
Measurements of electric field strengths in ionization fronts during plasma breakdown
Phys. Rev. Lett., 98, 075002, 2007

E. Wagenaars, M.D. Bowden, G.M.W. Kroesen
Measuring electric fields with laser-induced fluorescence-dip Stark spectroscopy
High Temp. Material Processes, 11, 455, 2007

W.J.M. Brok, E. Wagenaars, J. van Dijk, J.J.A.M. van der Mullen
Numerical description of pulsed breakdown between parabolic electrodes
IEEE Trans. Plasma Sci., 35, 1325, 2007

E. Wagenaars, M.D. Bowden, G.M.W. Kroesen
Investigations of Stark effects in xenon Rydberg states by laser-induced fluorescence-dip spectroscopy
Phys. Rev. A, 74, 033409, 2006

E. Wagenaars, N.W.B. Perriëns, W.J.M. Brok, M.D. Bowden, E.M. van Veldhuizen, G.M.W. Kroesen
Pre-breakdown light emission phenomena in low-pressure argon between parabolic electrodes
J. Phys. D: Appl. Phys. 39, 3831, 2006

E. Wagenaars, R. Brandenburg, W.J.M. Brok, M.D. Bowden, H.-E.Wagner
Experimental and modelling investigations of a dielectric barrier discharge in low-pressure argon
J. Phys. D: Appl. Phys. 39, 700, 2006

T. Jiang, M.D. Bowden, E. Wagenaars, E. Stoffels, G.M.W. Kroesen
Diagnostics of electric fields in plasma using Stark spectroscopy of krypton and xenon atoms
New J. Phys., 8, 202, 2006

T. Jiang, M.D. Bowden, E. Wagenaars, E. Stoffels, G.M.W. Kroesen
A study of Stark effects of Rydberg p states of noble gas atoms
J. Phys. D: Appl. Phys, 39, 5216, 2006

E. Wagenaars, M.D. Bowden, G.M.W. Kroesen
Plasma emission imaging of a low-pressure argon breakdown
Plasma Sources Sci. Technol., 14, 342, 2005

E. Wagenaars, M.D. Bowden, G.M.W. Kroesen
Plasma emission imaging of electrical breakdown in low-pressure argon
IEEE Trans. Plasma Sci., 33, 254, 2005

T. Jiang, M.D. Bowden, E. Wagenaars, G.M.W. Kroesen
Emission imaging of a PDP-like microdischarge
IEEE Trans. Plasma Sci., 33, 506, 2005

M.D. Bowden, E. Wagenaars, T. Jiang, W.J.M. Brok, M.F. Gendre
Measurements of plasma breakdown
High Temp. Material Processes, 8, 483, 2004