1. R. Nagaoka, A. Nadji, M.E. Couprie, O. Marcouillé
Study the effects of a Robinson wiggler at SOLEIL towards brightness increase
H. Abualrob, P. Brunelle, M. Labat, L. Cassinari, M.A. Tordeux, L. Nadolski,
R. Nagaoka, A. Nadji, M.E. Couprie, O. Marcouillé

2. H. Abualrob Journées Accélérateur, Roscoff, october 2013
Outline
Synchrotron radiation & its properties
Robinson wiggler & emittance reduction
Experimental observation of Robinson SOLEIL
Predicted influence of a Robinson wiggler on the spectral performances
Preliminary magnetic design of Robinson wiggler
H. Abualrob Journées Accélérateur, Roscoff, october 2013

3. Light source A bright photon beam is: Intense
Emitted from a small size and low divergence source
Monochromatic
H. Abualrob Journées Accélérateur, Roscoff, october 2013

4. H. Abualrob Journées Accélérateur, Roscoff, october 2013
Synchrotron SOLEIL
Energy
2.75 GeV
Circumference
354 m
Emittance H
3.9 nm.rad
Emittance V
39 pm.rad
Current mA
Beam lifetime (bare machine)
15 h
beamlines 26
Spectral range
IR to hard X-ray
H. Abualrob Journées Accélérateur, Roscoff, october 2013

5. Beam Brightness and emittance
𝝈𝒑𝒉
𝝈 ′ 𝒑𝒉 e-
Effective emittance is the beam size 𝝈𝒑𝒉
times the angular divergence 𝝈 ′ 𝒑𝒉
Effective photon beam emittance
Effective electron beam emittance
Beam size
Beam divergence
high brightness low emittance 
H. Abualrob Journées Accélérateur, Roscoff, october 2013

6. Energy spread & bunch length
Number of electrons
Energy of electrons
Energy spread L
L+ΔL
Momentum compaction factor
Bunch length in seconds
Energy spread
Synchrotron frequency
H. Abualrob Journées Accélérateur, Roscoff, october 2013

7. Emittance reduction: motivation
Spectroscopy
high spectral resolution
high flux through narrow slit
Crystallography
high angular resolution
wavelength matching to crystal dimensions
High flux within small beam size and divergence
High brightness  low emittance (H & V)
H. Abualrob Journées Accélérateur, Roscoff, october 2013

8. Emittance reduction methods
Increasing the number of dipoles: MAX IV
S. Leemans, Phys. Rev. Spec. Topics AB 12, , 2009.
Introducing a transverse gradient in the dipoles: ALBA
D. Einfeld, Status of ALBA project, IPAC10, Japan.
Installing tens of meters of damping wigglers: PETRA III
M. Tischer, Damping wigglers for PETRA III light source, proceeding PAC05, Knox ville, Tennessee.
Installing a Robinson wiggler
H. Abualrob Journées Accélérateur, Roscoff, october 2013

9. H. Abualrob Journées Accélérateur, Roscoff, october 2013
Robinson wiggler
Robinson wiggler: magnetic system of alternated field gradient superimposed to the main field, to be installed in a non-zero dispersion straight section (1)
Compact, less expensive, can be adopted by compact & large machines s x
B dB/dx<0
Parameter
Equation
present
With Robinson wiggler
Damping partition
Horizontal emittance
Energy spread
(1) K. W. Robinson, Radiation effects in circular electron accelerators, physical review, vol. 111, number 2, 1958.
H. Abualrob Journées Accélérateur, Roscoff, october 2013

10. H. Abualrob Journées Accélérateur, Roscoff, october 2013
Previous projects
First Cambridge Electron Accelerator (CEA)
A. Hofmann, Design and performance of the damping system for beam storage in the CEA, ICHEA, Cambridge, 1967.
Installtion in the CERN showing 50% horizontal emittance reduction
Y. Baconnier et al, Emittance control of the PS e+/e beams using a Robinson wiggler, Nucl. Instr. and Meth. in Physics Research A234 (1985)
H. Abualrob Journées Accélérateur, Roscoff, october 2013

11. H. Abualrob Journées Accélérateur, Roscoff, october 2010
Experimental study of Robinson effects on: -The horizontal emittance -The energy SOLEIL
H. Abualrob Journées Accélérateur, Roscoff, october 2010

12. Robinson effect @ SOLEIL
Presently, there is no Robinson SOLEIL !
IDEA…
Use the 4 undulators U20 to obtain a strong periodic magnetic field
Simultaneous off-axis propagation in the 4 undulators to create a periodic field gradient
Measure the transverse beam size using a pinhole camera
Measure the bunch length using a streak camera e-
H. Abualrob Journées Accélérateur, Roscoff, october 2013

13. The in vacuum undulator U20
Gap
5.5 mm
Bmax
0.97 T K
1.8
Period length
20 mm
No. of periods 98
H. Abualrob Journées Accélérateur, Roscoff, october 2013

14. Beam size measurement to deduce the emittance variation
Beam size measurement using a pinhole camera
H. Abualrob Journées Accélérateur, Roscoff, october 2013

15. Bunch length measurement to deduce the energy spread variation
Bunch length measurement using a streak camera
H. Abualrob Journées Accélérateur, Roscoff, october 2013

16. H. Abualrob Journées Accélérateur, Roscoff, october 2013
Emittance reduction, energy spread increase & spectral performances with a Robinson wiggler
Assuming that a Robinson wiggler is SOLEIL
Assuming horizontal emittance reduction by a factor of 2 (from 3.9 nm rad to 1.95 nm rad)
Assuming energy spread increase by
(from to )
H. Abualrob Journées Accélérateur, Roscoff, october 2013

17. Photon flux calculation/low energy range
Undulator
HU640
Type
Helical/EM
Period (mm)
640
Bz (T)
0.15 K
8.9
Flux calculation with SRW (1) through an aperture of 0.1 * 0.1 mm2 10 m from the source
(1) O. Chubar, Accurate and efficient computation of synchrotron radiation in the near field region, EPAC 98, Stockholm.
H. Abualrob Journées Accélérateur, Roscoff, october 2013

18. Photon flux calculation/high energy range
undulator
U20
Type
planar/PM
Period (mm) 20
Bz (T)
1.08 K 2
Flux calculation with SRW through an aperture of 0.1 * 0.1 mm2 10 m from the source
H. Abualrob Journées Accélérateur, Roscoff, october 2013

19. Brightness calculation
Brightness decrease for low energy range (HU640)
Remember that
90% Brightness increase for high energy range (U20)
H. Abualrob Journées Accélérateur, Roscoff, october 2013

20. Robinson wiggler...preliminary magnetic design
Gap
6 mm
Bmax
-2.5 T
193 T2
Period length
164 mm
Wiggler length
2 m e-
Design performed using RADIA code. O. Chubar, Computing 3D magnetic fields from insertion devices, PAC 1997, Vancouver, Canada.
H. Abualrob Journées Accélérateur, Roscoff, october 2013

21. H. Abualrob Journées Accélérateur, Roscoff, october 2013
Conclusion
Robinson effects on reducing the emittance and increasing the energy spread were observed and validated experimentally, for the first time, in a synchrotron light source at SOLEIL.
Considering a Robinson wiggler at SOLEIL reduces the emittance, leading to brightness increase “in the high energy range”. However, Robinson wiggler increases the energy spread leading to flux reduction.
H. Abualrob Journées Accélérateur, Roscoff, october 2013

22. Thank you for your attention
H. Abualrob Journées Accélérateur, Roscoff, october 2013