Free Electron Laser Studies. David Dunning MaRS ASTeC STFC Daresbury Laboratory. Free Electron Laser (FEL) Studies. What is a free electron laser? And why are we interested? How does a free electron laser work? What is the current state of the art? What are we working on?
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STFC Daresbury Laboratory
Extremely useful output properties:
Accelerator-based photon source that operates through the transference of energy from a relativistic electron beam to a radiation field.
Resonant emission – electron bunching
Electrons bunch at resonant radiation wavelength – coherent process
Axial electron velocity
Low-gain FELs use a short undulator and a high-reflectivity optical cavity to increase the radiation intensity over many undulator passes
High-gain FELs use a much longer undulator section to reach high intensity in a single pass
Self-amplified spontaneous emission (SASE)
*B W J McNeil, J A Clarke, D J Dunning, G J Hirst,
H L Owen, N R Thompson, B Sheehyand P H Williams,
Proceedings FEL 2006
New Journal of Physics 9, 82 (2007)
SASESpike FWHM ~ 10fs
Mode-CoupledSpike FWHM ~ 1 fs
Mode-LockedSpike FWHM ~ 400 as
Neil Thompson and Brian McNeil, PRL, 2007
Mode locking mechanism
Brian McNeil, David Dunning, Neil Thompson and Brian Sheehy, Proceedings of FEL08
HHG amplification mechanism
HHG amplification mechanism with energy modulation period and slippage at multiple of pulse spacing