The EPS Plasma Physics Division is happy to announce the winners of the EPS PPD PhD Research Award. The Selection Committee had following members : Alexander Andreev, Arutiun Ehiasarian, Enzo Lazzaro and Michel Chatelier.

The Selection Committee proposed 4 candidates for the award:

• Giada Cantono
• Eleanor Tubman
• Francisco Javier Artola Such and
• Michael Faitsch

Candidates and citations

Candidate: Giada Cantono

Nominator: Marco Borghesi

Title of PhD thesis: Relativistic plasmonics for ultra-short radiation sources

Univ./Inst:  Université Paris-Saclay and Università di Pisa

Citation: The thesis of Giada Cantono “Relativistic plasmonics for ultra-short radiation sources” demonstrates the opportunity of resonant surface plasmon (SP) excitation at ultra-high laser intensities by studying how such waves accelerate bunches of relativistic electrons along the target surface and how they enhance the generation of high-order harmonics of the laser frequency. Both these processes have been investigated with numerous experiments and extensive numerical simulations. Adopting a standard configuration from classical plasmonics, SPs are excited on solid, wavelength-scale grating targets. In their presence, both electron and harmonic emissions exhibit remarkable features that support the conception of practical applications. Putting aside some major technical and conceptual issues discouraging the applicability of plasmonic effects in the high-field regime, these results are expected to mark new promises to the exploration of Relativistic Plasmonics.

Candidate: Eleanor Tubman

Nominator: Nigel Woolsey

Title of PhD thesis: Magnetic field generation in laser-plasma interactions

Univ./Inst: University of York

Citation: In the thesis of Eleanor Tubman “Magnetic field generation in laser-plasma interactions” the primary focus is the understanding of the different mechanism of magnetic field production during laser-plasma experiments. The first one is from the by-product of launching asymmetric shocks. The second looks at the reconnection of magnetic fields between two laser focal spots and the third is from fields produced around a current carrying loop target The coupling of the laser energy into the shock wave is calculated to be 2%. It was experimentally demonstrate that when two laser spots are placed in close proximity reconnection occurs. Diagnostics, including proton radiography, X-ray detectors and an optical probe, record and diagnose the existence of a semi-collisional reconnection event. Magnetic fields are produced by driving a current through a loop attached to two plates and new measurements recording the voltages induced are presented in this thesis. Ideas for furthering this research to enhance our understanding in this area are given.

Candidate: Francisco Javier Artola Such

Nominator: Guido Huijsmans

Title of PhD thesis: Free-boundary simulations of MHD plasma instabilities in tokamaks

Univ./Inst: Université Aix-Marseille

Citation: The PhD works of Javier Artola address a central question for magnetic fusion energy, with major potential consequences for the next step device, ITER. In the standard operational regime of ITER, periodic relaxations (ELMs) of the edge plasma pressure may both affect plasma confinement and deteriorate plasma facing materials. Controlling these instabilities in a practical way is thus mandatory.

A major step toward this control is the development of an accurate and comprehensive numerical tool capable of describing the experimental observations and developing the adequate control scenarios for the future. This is the aim of the JOREK-STARWALL code, a free boundary simulation of MHD plasma instabilities coupled to the detailed tokamak structures where induced currents need to be calculated accurately.

The most visible result obtained in the frame of the PhD is the clear demonstration of ELM control by vertical plasma kicks which trigger ELMS. This result is fully explained by 3D simulations. Other important contributions relate to the development of halo currents in the machine structures when the plasma becomes vertically unstable. Javier Artola has made very general predictions for the halo currents development in ITER which will be very useful for minimizing their impact on the tokamak structures.

The prudent approach of Javier Artola of developing analytical codes in parallel to the full 3D simulations should be noted, giving confidence that the code predictions lay inside limits that can be justified.

The contribution of Javier Artola to the development of JORK-STARWALL, the code simulations of experimental results already accomplished and the application to the ITER geometry are outstanding achievements and give confidence that the magnetic fusion community has in hands a highly performing tool capable of assisting ITER operation since the beginning.

Candidate: Michael Faitsch

Nominator: Hartmut Zohm

Title of PhD thesis: Divertor Power Load Studies at ASDEX Upgrade and TCV

Univ./Inst: Ludwig-Maximilians-Universität München, at Max-Planck-Institut für Plasmaphysik

Citation: The thesis work of M. Faitsch is well focused on the problem of the effect of magnetic perturbation breaking the axisymmetry of a tokamak on the heat flux pattern on the divertor target looking up to high performance scenarios, in L-Mode conditions as well as H-Mode. Attention is given to changes in steady state heat flux compared to heat flux without a magnetic perturbation present.

The questions specifically addressed by the author are all very meaningful for reactor oriented devices:

• How does the application of a magnetic perturbation change scrape-off layer heat transport?

• How does transport in the divertor region change the heat flux pattern on the divertor target in presence of an external magnetic perturbation?

• What are the differences between L-Mode and inter-ELM heat fluxes in presence of an external magnetic perturbation?

• How are ELM heat loads affected by the application of a magnetic perturbation?

The approach used in this work blends theoretical competence (and rigor) with concrete modeling of realistic situations (for AUG) with interesting technical proposals. The experimental results are new, to my knowledge and this research deserves encouragement to be continued and extended.

The conclusion that applying an external non axisymmetric magnetic perturbation leads to a major change in the divertor heat flux pattern and the inter-ELM and L-mode pattern is extremely important, practically and theoretically.

More information about EPS Plasma Physics Division and the award on the division's website: http://plasma.ciemat.es/eps/