Novel Methods for Short Wavelength Free Electron Lasers

The spatial and temporal resolution available from high brightness X-ray pulses with optional attosecond duration, would make feasible the observation and ultimately the potential to control ultra-fast, optionally non-linear, atomic processes. With the ability to probe correlated electronic processes within atoms at these spatial and temporal scales, to measure how electrons and nuclei reorganise themselves, either individually within atoms due to external stimulus, during molecular bond making and breaking, or while undergoing subtle catalytic or biological processes, we can begin to unravel how all matter functions at this fundamental level.

Such x-ray pulse generation requires a 3D computational model of the Free Electron Laser which is capable of modelling electron interactions with broad bandwidth radiation. In collaboration with staff of the UK’s Science and Technology Facilities Council (STFC) at their Accelerator Science and Technology Centre (ASTeC), Dr Brian McNeil’s group at the University of Strathclyde has developed several new methods that have the potential to generate such pulses from Free Electron Lasers (FEL). These methods may improve two key measures of X-ray output quality from Free Electron Lasers by two orders of magnitude that could transform the science that we can do. For example, for the first time X-ray pulse durations and brightness may enable unexplored electron/nuclear interactions within the atom to be probed. These methods will be developed and subject to experimental research at the proposed Compact Linear Accelerator for Research and Applications (CLARA) facility based at STFC Daresbury Laboratory, and will feed into any future UK high brightness light source design. Collaborations with Prof Hidding of the Strathclyde SCAPA project are also beginning to investigate multi-beamlet ‘Trojan horse’ plasma accelerator output as FEL potential drivers.

In addition to being of national importance for STFC facility development, the research has international importance by influencing and potentially directly affecting the design and development of international light source facilities in Germany, Switzerland, the USA and Japan. Currently, the Strathclyde group and STFC ASTeC are collaborating with two such major international facilities at DESY, Germany, where we are collaborating in plasma accelerator driven FELs, and the Paul Scherrer Institute, Switzerland, where we are collaborating in multi-colour FEL interactions.

The primary aims of this proposal is to further develop the research of the group into the generation of high brightness x-ray photon pulses that would allow the spatiotemporal imaging of events at the atomic scale (~1 Å, ~10 as (atto-second)).

A new parallel code ‘PUFFIN’ (Parallel Unaveraged Fel INtegrator) has been developed by the group’s Dr Lawrence Campbell and Dr Brian McNeil. The group is very interested in developing the code, its user interface, data post-processing and visualisation. The primary aim of PUFFIN is to provide a flexible research resource that can be adapted to test new ideas and methods for future FEL development. It is written in FORTRAN 90 using the MPI standard.

For more information about the project contact Dr Brian McNeil, (b.w.j.mcneil@strath.ac.uk), Reader at the Department of Physics at the University of Strathclyde.

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