IPAC2012 - List of Authors (Abualrob, H.B.)

Paper	Title	Page
MOPPP062	Soleil Emittance Reduction using a Robinson Wiggler	702
	H.B. Abualrob, P. Brunelle, M.-E. Couprie, O. Marcouillé, A. Nadji, L.S. Nadolski, R. Nagaoka SOLEIL, Gif-sur-Yvette, France
	For both synchrotron light sources as SOLEIL and colliders, the emittance is one of the key parameters to increase the photon brightness and the beam luminosity. In order to decrease the emittance, the ring optics is built on very focusing lattices leading to large chromaticities and potential reduction of the dynamics aperture and momentum transverse acceptance. Thus, some facilities have installed damping wigglers in zero dispersion straight sections to relax the optics and to reach sub-nanometer horizontal emittances. This solution requires however tens or hundreds meters of insertion devices. For storage ring equipped with zero-gradient bending magnets, an alternative solution can be given by installing a single Robinson wiggler [1] in a dispersive section enabling to divide the emittance by a factor 2. The uniqueness of this wiggler results from the presence of an alternated gradient superimposed the main periodic magnetic field. This paper recalls the concept of the wiggler, presents the expected gain for SOLEIL storage ring with the impact on the linear optics and the brightness. A preliminary magnetic design is also proposed. [1] K.W. Robinson, Phys. Rev, p. 373 (1958).

TUPPP048	Increasing the Spectral Range of the CLIO Infrared FEL User Facility by Reducing Diffraction Losses	1709
	J.-M. Ortega, G. Perilhous, R. Prazeres LCP/CLIO, ORSAY CEDEX, France H.B. Abualrob, P. Berteaud, L. Chapuis, M.-E. Couprie, T.K. El Ajjouri, F. Marteau, J. Vétéran SOLEIL, Gif-sur-Yvette, France J.P. Berthet, F. Glotin CLIO/ELISE/LCP, Orsay, France
	Funding: CNRS/RTRA The infrared free-electron laser offers a large tunability since the FEL gain remains high throughout the infrared spectral range, and the reflectivity of metal mirrors remains also close to 1. The main limitation comes from the diffraction of the optical beam due to the finite size of the vacuum chamber of the undulator. At CLIO, we have obtained previously* an FEL tunable from 3 to 150 μm by operating the accelerator between 50 and 14 MeV. However, we found that a phenomenon of “power gaps“ is observed in far-infrared : the laser power falls down to zero at some particular wavelengths, whatever the beam adjustments are. We showed that this effect is related to to the waveguiding effect of the vacuum chamber leading to different losses and power outcoupling at different wavelengths*. To alleviate this effect we have designed a new undulator allowing to use a larger vacuum chamber without reducing the spectral tunability and agility of the FEL. From simulations, a large increase of available power is expected in far-infrared. The new undulator has been installed and its performances and first FEL measurement in far-infrared will be presented J.M. Ortega, F. Glotin, R. Prazeres Infrared Physics and Technology, 49, 133 (2006) ** R. Prazeres, F. Glotin, J.-M. Ortega Phys. Rev. STAB12, 010701 (2009)

Paper

Title

Page

Soleil Emittance Reduction using a Robinson Wiggler

702

H.B. Abualrob, P. Brunelle, M.-E. Couprie, O. Marcouillé, A. Nadji, L.S. Nadolski, R. Nagaoka
SOLEIL, Gif-sur-Yvette, France

For both synchrotron light sources as SOLEIL and colliders, the emittance is one of the key parameters to increase the photon brightness and the beam luminosity. In order to decrease the emittance, the ring optics is built on very focusing lattices leading to large chromaticities and potential reduction of the dynamics aperture and momentum transverse acceptance. Thus, some facilities have installed damping wigglers in zero dispersion straight sections to relax the optics and to reach sub-nanometer horizontal emittances. This solution requires however tens or hundreds meters of insertion devices. For storage ring equipped with zero-gradient bending magnets, an alternative solution can be given by installing a single Robinson wiggler [1] in a dispersive section enabling to divide the emittance by a factor 2. The uniqueness of this wiggler results from the presence of an alternated gradient superimposed the main periodic magnetic field. This paper recalls the concept of the wiggler, presents the expected gain for SOLEIL storage ring with the impact on the linear optics and the brightness. A preliminary magnetic design is also proposed. [1] K.W. Robinson, Phys. Rev, p. 373 (1958).

TUPPP048

Increasing the Spectral Range of the CLIO Infrared FEL User Facility by Reducing Diffraction Losses

1709

J.-M. Ortega, G. Perilhous, R. Prazeres
LCP/CLIO, ORSAY CEDEX, France
H.B. Abualrob, P. Berteaud, L. Chapuis, M.-E. Couprie, T.K. El Ajjouri, F. Marteau, J. Vétéran
SOLEIL, Gif-sur-Yvette, France
J.P. Berthet, F. Glotin
CLIO/ELISE/LCP, Orsay, France

Funding: CNRS/RTRA
The infrared free-electron laser offers a large tunability since the FEL gain remains high throughout the infrared spectral range, and the reflectivity of metal mirrors remains also close to 1. The main limitation comes from the diffraction of the optical beam due to the finite size of the vacuum chamber of the undulator. At CLIO, we have obtained previously* an FEL tunable from 3 to 150 μm by operating the accelerator between 50 and 14 MeV. However, we found that a phenomenon of “power gaps“ is observed in far-infrared : the laser power falls down to zero at some particular wavelengths, whatever the beam adjustments are. We showed that this effect is related to to the waveguiding effect of the vacuum chamber leading to different losses and power outcoupling at different wavelengths**. To alleviate this effect we have designed a new undulator allowing to use a larger vacuum chamber without reducing the spectral tunability and agility of the FEL. From simulations, a large increase of available power is expected in far-infrared. The new undulator has been installed and its performances and first FEL measurement in far-infrared will be presented
* J.M. Ortega, F. Glotin, R. Prazeres
Infrared Physics and Technology, 49, 133 (2006)
** R. Prazeres, F. Glotin, J.-M. Ortega
Phys. Rev. STAB12, 010701 (2009)