CERN Accelerating science

Article
Report number	SLAC-PUB-11190
Title	Cavity Alignment Using Beam Induced Higher Order Modes Signals in the TTF Linac
Author(s)	Ross, Marc ; Baboi, Nicoleta ; Frisch, Josef ; Hacker, Kirsten E ; Jones, Roger M ; McCormick, Douglas ; Napoly, Olivier ; Paparella, Rita ; Smith, Tonee ; Wendt, Manfred
Affiliation	(CEA/DSM/DAPNIA, Gif-sur-Yvette) ; (DESY, Hamburg) ; (SLAC)
Publication	2005
Imprint	6 Jul 2005
Number of pages	3
In:	21st IEEE Particle Accelerator Conference, Knoxville, TN, USA, 16 - 20 May 2005, pp.2284
Abstract	Each nine cell superconducting accelerator cavity in the TESLA Test Facility (TTF) at DESY* has two higher order mode (HOM) couplers that efficiently remove the HOM power.** They can also provide useful diagnostic signals. The most interesting modes are in the first 2 cavity dipole passbands. They are easy to identify and their amplitude depends linearly on the beam offset from the cavity axis making them excellent beam position monitors (BPM). By steering the beam through an eight-cavity cryomodule, we can use the HOM signals to estimate internal residual alignment errors and minimize wakefield related beam emittance growth. We built and commissioned a four channel heterodyne receiver and time-domain based waveform recorder system that captures information from each mode in these two bands on each beam pulse. In this paper we present an experimental study of the single-bunch generated HOM signals at the TTF linac including estimates of cavity alignment precision and HOM BPM resolution.

Corresponding record in: Inspire