TTF HOM Data Analysis with Curve Fitting Method.

Pei, S. ; Adolphsen, C. ; Li, Z. ; Bane, K. ; Smith, J.

Technical Information Center Oak Ridge Tennessee

关键词: Accelerators;    Amplitudes;    Beam position;    Cavities;    Data analysis;   

RP-ID  :  DE2008933008

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

To investigate the possibility of using HOM signals induced in SC cavities as beam and cavity diagnostics, narrow band (20 MHz) data was recorded around the strong TE111-6(6(pi)/9-like) dipole modes (1.7 GHz) in the 40 L-band (1.3 GHz) cavities at the DESY TTF facility. The analyses of these data have so far focused on using a Singular Value Decomposition (SVD) technique to correlate the signals with each other and data from conventional BPMs to show the dipole signals provide an alternate means of measuring the beam trajectory. However, these analyses do not extract the modal information (i.e., frequencies and Q's of the nearly degenerate horizontal and vertical modes). In this paper, we described a method to fit the signal frequency spectrum to obtain this information, and then use the resulting mode amplitudes and phases together with conventional BPM data to determine the mode polarizations and relative centers and tilts. Compared with the SVD analysis, this method is more physical, and can also be used to obtain the beam position and trajectory angle.