CERN Accelerating science

Article
Title	The Influence of Tuners and Temperature on the Higher Order Mode Spectrum for 1.3 GHz SCRF Cavities
Author(s)	Ainsworth, R (Royal Holloway, U. of London) ; Molloy, S (ESS, Lund) ; Zhang, P (CERN) ; Grecki, M (DESY) ; Baboi, N (DESY) ; Wamsat, T (DESY) ; Eddy, N (Fermilab)
Publication	2013
Number of pages	3
In:	16th International Conference on RF Superconductivity, Paris, France, 23 - 27 Sep 2013, pp.thp048
Abstract	Higher Order Modes (HOMs) are of concern for superconducting cavities as they can drive instabilities and so are usually damped and monitored. With special dedicated electronics, HOMs can provide information on the position on the beam. It has been proposed that piezo tuners used to keep the cavities operating at 1.3 GHz could alter the HOM spectrum altering the calibration constants used to read out the beam position affecting long term stability of the system. Also, of interest is how the cavity reacts to the slow tuner. Detuning and the retuning the cavity may alter the HOM spectrum. This is of particular interest for future machines not planning to use dedicated HOM damping as the tuning procedure may shift the frequency of HOMs onto dangerous resonances. The effect of temperature on the HOM spectrum is also investigated. An investigation of these effects has been performed at FLASH and the results are presented.
Copyright/License	publication: (License: CC-BY)