Title :
Effect of TE mode power on the PEP-II LER BPM system
Author :
Corlett, J. ; Ng, C.K. ; Smith, S.R.
Author_Institution :
Lawrence Berkeley Nat. Lab., CA, USA
Abstract :
The beam chamber of the PEP-II B-Factory Low Energy Ring (LER) arc sections is connected to an antechamber for the absorption of synchrotron radiation on discrete photon stops. The presence of the antechamber substantially reduces the cutoff frequency of the vacuum chamber and, in particular, allows the propagation of higher-order-mode (HOM) TE power generated by beamline components at the BPM signal processing frequency. Calculations of the transmission properties of the TE mode in different sections of the vacuum chamber show that the power is trapped between widely separated bellows in the arc sections. Because of the narrow signal bandwidth and weak coupling of the TE mode to the BPM buttons, the noise contributed by the HOM TE power will not produce a noticeable effect on the BPM position signal voltage
Keywords :
accelerator RF systems; electron accelerators; particle beam diagnostics; storage rings; BPM buttons; BPM signal processing frequency; Low Energy Ring; PEP-II B-Factory; arc sections; beam chamber; beam position monitors; bellows; cutoff frequency; discrete photon stops; higher-order-mode TE power; position signal voltage; synchrotron radiation; transmission properties; vacuum chamber; Absorption; Bandwidth; Bellows; Cutoff frequency; Power generation; Signal generators; Signal processing; Synchrotron radiation; Tellurium; Vacuum arcs;
Conference_Titel :
Particle Accelerator Conference, 1997. Proceedings of the 1997
Conference_Location :
Vancouver, BC
Print_ISBN :
0-7803-4376-X
DOI :
10.1109/PAC.1997.751126
