FEL2017 - List of Authors (Thompson, N.)

Paper	Title	Page
TUP059	Alternative Electron Beam Slicing Methods for CLARA and X-ray FELs	352
	D.J. Dunning, H.M. Castaneda Cortes, S.P. Jamison, T.A. Mansfield, N. Thompson, D.A. Walsh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom D. Bultrini, S.P. Jamison, N. Thompson Cockcroft Institute, Warrington, Cheshire, United Kingdom D. Bultrini University of Glasgow, Glasgow, Scotland, United Kingdom
	Methods to generate ultra-short radiation pulses from X-ray FELs commonly slice a relatively long electron bunch to feature one (or more) short regions of higher beam quality which then lase preferentially. The slotted foil approach spoils the emittance of all but a short region, while laser-based alternatives modulate the electron beam energy, improving potential synchronisation to external sources. The CLARA FEL test facility under development in the UK will operate at 100-400 nm, aiming to demonstrate FEL schemes applicable at X-ray wavelengths. We present new laser-based slicing schemes which may better suit the wavelength range of CLARA and provide options for X-ray facilities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUP059
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MOP039	Possible Method for the Control of SASE Fluctuations	129
	N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	It is well known that because the SASE FEL starts up from the intrinsic electron beam shot noise, there are corresponding fluctuations in the useful properties of the output pulses which restrict their usability for many applications. In this paper, we discuss possible new methods for controlling the level of fluctuations in the output pulses.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP039
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WEC02	Optimization of Superconducting Undulators for Low Repetition Rate FELs	411
	J.A. Clarke, K.B. Marinov, B.J.A. Shepherd, N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom V. Bayliss, J. Boehm, T.W. Bradshaw, A.J. Brummitt, S.J. Canfer, M.J.D. Courthold, B. Green, T. Hayler, P. Jeffery, C. Lockett, D.S. Wilsher STFC/RAL, Chilton, Didcot, Oxon, United Kingdom S. Milward, E.C.M. Rial DLS, Oxfordshire, United Kingdom
	Superconducting undulators (SCUs) optimized for storage rings and MHz-level FELs require an intermediate beam screen to intercept the power deposited by the electron beam, due to resistive wall wakefields, to prevent magnet quenching. This beam screen increases the magnet gap by around 2 mm which is a significant increase when compared to the typical electron beam aperture of around 5 mm. However, lower repetition rate FELs only deposit of the order of tens of mW/m and so the beam screen is no longer needed resulting in a significant reduction in undulator magnet gap. We have investigated the impact of this reduced magnet gap and found that the magnetic field level increases greatly. For example, an SCU with a 15 mm period and 5 mm aperture optimized for a low repetition rate FEL instead of a storage ring will generate a field of 2.1 T compared to 1.4 T. Such a major increase in undulator performance could have a significant impact on the optimization of FELs. This paper describes how an SCU optimized for application in a FEL will be able to generate magnetic field levels far beyond those currently foreseen for any other magnet technology.
	Slides WEC02 [6.234 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEC02
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WEP062	Optical Beam Quality Analysis of the Clara Test Facility Using Second Moment Analysis	543
	H.M. Castaneda Cortes, D.J. Dunning, M.D. Roper, N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	We studied and characterised the FEL optical radiation in simulations of the CLARA FEL test facility under development at Daresbury Laboratory in the UK. In particular, we determined the optical beam quality coefficient, waist position and other source properties corresponding to different potential FEL operating modes via wavefront propagation in free space using OPC (Optical Propagation Code) and Second Moment Analysis. We were able to find the operation mode and undulator design for which the optical beam has the optimum quality at highest brightness. Furthermore, we studied the way that different properties of the electron bunches (emittance, peak current, bunch length) affect the optical beam. We are now able to understand how the optical beam will propagate from the end of the undulator and through the photon transport system to the experimental stations. This knowledge is necessary for the correct design of the photon transport and diagnostic systems.
	Poster WEP062 [0.495 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP062
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Paper

Title

Page

Alternative Electron Beam Slicing Methods for CLARA and X-ray FELs

352

D.J. Dunning, H.M. Castaneda Cortes, S.P. Jamison, T.A. Mansfield, N. Thompson, D.A. Walsh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
D. Bultrini, S.P. Jamison, N. Thompson
Cockcroft Institute, Warrington, Cheshire, United Kingdom
D. Bultrini
University of Glasgow, Glasgow, Scotland, United Kingdom

Methods to generate ultra-short radiation pulses from X-ray FELs commonly slice a relatively long electron bunch to feature one (or more) short regions of higher beam quality which then lase preferentially. The slotted foil approach spoils the emittance of all but a short region, while laser-based alternatives modulate the electron beam energy, improving potential synchronisation to external sources. The CLARA FEL test facility under development in the UK will operate at 100-400 nm, aiming to demonstrate FEL schemes applicable at X-ray wavelengths. We present new laser-based slicing schemes which may better suit the wavelength range of CLARA and provide options for X-ray facilities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUP059

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOP039

Possible Method for the Control of SASE Fluctuations

129

N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

It is well known that because the SASE FEL starts up from the intrinsic electron beam shot noise, there are corresponding fluctuations in the useful properties of the output pulses which restrict their usability for many applications. In this paper, we discuss possible new methods for controlling the level of fluctuations in the output pulses.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP039

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEC02

Optimization of Superconducting Undulators for Low Repetition Rate FELs

411

J.A. Clarke, K.B. Marinov, B.J.A. Shepherd, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
V. Bayliss, J. Boehm, T.W. Bradshaw, A.J. Brummitt, S.J. Canfer, M.J.D. Courthold, B. Green, T. Hayler, P. Jeffery, C. Lockett, D.S. Wilsher
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
S. Milward, E.C.M. Rial
DLS, Oxfordshire, United Kingdom

Superconducting undulators (SCUs) optimized for storage rings and MHz-level FELs require an intermediate beam screen to intercept the power deposited by the electron beam, due to resistive wall wakefields, to prevent magnet quenching. This beam screen increases the magnet gap by around 2 mm which is a significant increase when compared to the typical electron beam aperture of around 5 mm. However, lower repetition rate FELs only deposit of the order of tens of mW/m and so the beam screen is no longer needed resulting in a significant reduction in undulator magnet gap. We have investigated the impact of this reduced magnet gap and found that the magnetic field level increases greatly. For example, an SCU with a 15 mm period and 5 mm aperture optimized for a low repetition rate FEL instead of a storage ring will generate a field of 2.1 T compared to 1.4 T. Such a major increase in undulator performance could have a significant impact on the optimization of FELs. This paper describes how an SCU optimized for application in a FEL will be able to generate magnetic field levels far beyond those currently foreseen for any other magnet technology.

Slides WEC02 [6.234 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEC02

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEP062

Optical Beam Quality Analysis of the Clara Test Facility Using Second Moment Analysis

543

H.M. Castaneda Cortes, D.J. Dunning, M.D. Roper, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

We studied and characterised the FEL optical radiation in simulations of the CLARA FEL test facility under development at Daresbury Laboratory in the UK. In particular, we determined the optical beam quality coefficient, waist position and other source properties corresponding to different potential FEL operating modes via wavefront propagation in free space using OPC (Optical Propagation Code) and Second Moment Analysis. We were able to find the operation mode and undulator design for which the optical beam has the optimum quality at highest brightness. Furthermore, we studied the way that different properties of the electron bunches (emittance, peak current, bunch length) affect the optical beam. We are now able to understand how the optical beam will propagate from the end of the undulator and through the photon transport system to the experimental stations. This knowledge is necessary for the correct design of the photon transport and diagnostic systems.

Poster WEP062 [0.495 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP062

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)