Prof M Borghesi
Dr C Brown
No more applications being accepted
Funded PhD Project (European/UK Students Only)
The interaction of ultra-intense laser pulses with matter generates large currents of relativistic electrons whose flow into the irradiated targets and through their surfaces leads to the generation of very large, highly transient electric and magnetic fields. Mapping these fields with high spatial and temporal resolution is of high importance for a correct understanding of the dynamics of acceleration and transport of the energetic particles, and for benchmarking relevant numerical codes. Understanding and controlling the propagation of these large currents is also at the basis of important applications with strong societal impact, such as thermonuclear energy production via Inertial Confinement Fusion, or novel particle accelerators with potential use in future medical therapy.
Our group at QUB has been at the forefront of the detection of transient electromagnetic fields in plasmas for a number of years, through the application of proton radiography and deflectometry, techniques pioneered at QUB and applicable over a wide range of experimental conditions. Through high resolution field mapping, the PhD project will aim to investigate electron-driven dynamics in selected experimental contexts of particular topical interest.
An area of focus will be the transport of relativistic electrons through dense plasmas and solids. The ultralarge electron currents resulting from high power interactions can only propagate through a dense target by driving a neutralizing return current from the background, and this process is strongly affected by self-generated electromagnetic fields, both on microscopic and macroscopic spatial scales, which can lead to the development of a range of electro-magnetic instabilities. Time-resolved field mapping in the interior of extended targets can highlight signatures of these detrimental processes, and suggest methods for controlling them, with potential direct benefit to applications in nuclear fusion (Fast Ignition) and/or secondary source production (x-rays or ions). The project will also investigate the interaction of high intensity laser pulses with ultrathin foils, of direct relevance to advanced ion acceleration schemes. Field mapping through proton radiography, never attempted for these regimes, will provide also in this case clarification on the dynamics and spatial characteristics of the acceleration processes, with potential positive impact on future development of high energy ion sources for cancer therapy.
The project builds on an area of scientific excellence within QUB’s Centre for Plasma Physics, as recognized by the 2017 American Physical Society’s John Dawson Award for Excellence in Plasma Physics, and witnessed by a large number of publications in high profile journals. We envisage that this research will be mostly carried out on Petawatt-class facilities such as ORION (at AWE), VULCAN and GEMINI (at STFC’s Central Laser Facility), and will be supported by dedicated modelling with relevant codes.
Candidates must hold a 1st or 2.1 BSc/MSci (or equivalent) in Physics or relevant subject; a 1st MSci (or equivalent) is desirable.
The PhD position is available to UK nationals.
Applicants should apply electronically through the Queen's online application portal at: https://dap.qub.ac.uk/portal/
The project is jointly funded by QUB and AWE and offers a 42-months studentship available from 1 Oct 2020, which covers tuition fees, and a tax-free stipend of ~ £18,500 p.a.
L.Romagnani et al, Dynamics of the Electromagnetic Fields Induced by Fast Electron Propagation in Near-Solid-Density Media, Phys. Rev. Lett., 122, 025001 (2019)
H.Ahmed et al, Proton probing of laser-driven EM pulses travelling in helical coils, High Power Laser Science and Engineering, 5, 5, (2017)
A. Macchi, M. Borghesi, M. Passoni, Ion acceleration by superintense laser-plasma interaction, Rev. Modern Physics, 85, 751 (2013)