Title :
Gap Voltage Feed-Forward Module for PEP-II low level RF system
Author :
Ross, W. ; Claus, R. ; Sapozhnikov, L.
Author_Institution :
Linear Accel. Center, Stanford Univ., CA, USA
Abstract :
The Gap Voltage Feed-Forward (GVFF) Module produces adaptively generated inphase (I) and quadrature (Q) reference signals for a single RF station. This module measures the periodic (1-turn) beam induced cavity transients caused by the presence of an ion clearing gap in the beam. A reference waveform is generated to minimize the direct feedback error signal transient caused by the gap. In addition, the GVFF module receives a fiber-optically connected, band-limited `kick´ signal from the Longitudinal Feedback System. The kick signal modulates the I and Q components of the RF reference causing the station to act as a `sub-woofer´ for the Longitudinal Feedback System. This process dampens low order coupled-bunch instabilities induced by the fundamental mode of the accelerating cavities. The GVFF Module also includes hardware for remote measurement and adjustment of the `kick´ transfer function
Keywords :
accelerator RF systems; accelerator control systems; control engineering computing; electron accelerators; feedforward; storage rings; Gap Voltage Feed-Forward Module; Longitudinal Feedback System; PEP-II; beam induced cavity transients; coupled-bunch instabilities; inphase; ion clearing gap; kick signal; low level RF system; quadrature; Demodulation; Digital signal processing; Feedback loop; Feedforward systems; Filters; Open loop systems; RF signals; Radio frequency; Transfer functions; Voltage;
Conference_Titel :
Particle Accelerator Conference, 1997. Proceedings of the 1997
Conference_Location :
Vancouver, BC
Print_ISBN :
0-7803-4376-X
DOI :
10.1109/PAC.1997.751210
