CERN Accelerating science

Report
Report number	CERN-PS-2002-020-AE
Title	Emittance Exchange by Crossing a Coupling Resonance
Author(s)	Carli, Christian ; Cyvoct, G ; Giovannozzi, Massimo ; Métral, Elias ; Métral, G (CERN) ; Steerenberg, R
Affiliation	(CERN)
Publication	2002
Imprint	12 Jun 2002
Number of pages	4
Series	(Beam Dynamics and Electromagnetic Fields)
In:	8th European Particle Accelerator Conference, Paris, France, 3 - 7 Jun 2002, pp.1157
Subject category	Accelerators and Storage Rings
Accelerator/Facility, Experiment	CERN PS
Free keywords	accelerator-theory ; coupling ; emittance ; linear-dynamics ; resonance
Abstract	When the working point of a synchrotron is shifted across a second-order difference resonance in the presence of weak linear coupling, it is possible to exchange the transverse emittances. This result goes beyond the classical theory, where only emittance sharing is predicted. Systematic experimental investigations of the phenomenon have been performed at the CERN PS Complex. In the PS-Booster, the measurement of the horizontal emittance is hampered by the contribution of the momentum spread to the beam size through dispersion. Based on the new mechanism, the horizontal emittance was measured in the vertical plane, where no dispersion is present, thus improving the overall accuracy. In the PS, detailed measurements of the emittance exchange process were performed. In parallel, an analytical theory was derived. The agreement between theory and experimental results is remarkable.
Copyright/License	publication: (License: CC-BY) © CERN (License: CC-BY-4.0)

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