CERN Accelerating science

Internal Note
Report number	CERN-ACC-NOTE-2019-0044
Title	MD 3290: Instability threshold measurements in the presence of a controlled external excitation
Author(s)	Tambasco, Claudia (EPFL - Ecole Polytechnique Federale Lausanne (CH)) ; Barranco, Javier (EPFL - Ecole Polytechnique Federale Lausanne (CH)) ; Buffat, Xavier (CERN) ; Metral, Elias (CERN) ; Mounet, Nicolas (CERN) ; Levens, Tom (CERN) ; Pieloni, Tatiana (EPFL - Ecole Polytechnique Federale Lausanne (CH))
Corporate author(s)	CERN. Geneva. ATS Department
Publication	2019
Imprint	11 Oct 2019
Number of pages	6
Subject category	Accelerators and Storage Rings
Processes	Beam-Beam Effects ; Beam Instabilities
Keywords	Accelerator physics ; Beam-beam effects ; Beam instabilities ; Beam Transfer Function ; Stability diagram
Abstract	During the MD 2722 an unexpected instability was observed at flat top energy during BTF measurements. Simulation studies have shown an decrease of the instability thresholds according to the impedance level when in the presence of a small external excitation amplitude. In this note we summarise the results of the MD 3290 devoted to measure the instability thresholds in the presence of a controlled external excitation introduced by the use of the BTF system. The MD procedure is described and the presented results will be used as a reference in order to avoid instabilities during future BTF measurements at flat top energy.
Submitted by	[email protected]