CERN Accelerating science

Article
Title	Beam Based HOM Analysis of Acceleating Structures at the TESLA Test Facility LINAC
Author(s)	Wendt, M ; Schreiber, S ; Gössel, A
Publication	2003
In:	6th European Workshop on Beam Diagnostics and Instrumentation for Particle Accelerators, Mainz, Germany, 5 - 7 May 2003, pp.83
Subject category	Accelerators and Storage Rings
Abstract	The beam emittance in future linear accelerators for high energy physics and SASE-FEL applications depends highly on the field performance in the accelerating structures, i.e. the damping of higher order modes (HOM). Besides theoretical and laboratory analysis (network analyzer), a beam based analysis technique was established [S. Fartoukh, et.al., Proceedings of the PAC99 Conference] at the TESLA Test Facility (TTF) linac. It uses a charge modulated beam of variable modulation frequency to excite dipole modes. This causes a modulation of the transverse beam displacement, which is observed at a downstream BPM and associated with a direct analysis of the modes at the HOM couplers. Emphasis of this presentation is put on beam instrumentation and signal analysis aspects. A brief introduction of eigenmodes in resonant structures, as well as some interesting measurement results are further presented.