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Paper	Title	Other Keywords	Page
DYN00	Feedback Control of SPS E-clouds / Transverse Mode Coupled Instabilities	feedback, controls, simulation, pick-up	50
	C. Rivetta, A. Bullitt, J. Fox, T. Mastorides, G. Ndabashimiye, M. Pivi, O. Turgut SLAC National Accelerator Laboratory R. Secondo, J. Vay LBNL W. Hofle, B. Salvant CERN
	Electron cloud driven instability can impose limitations on the maximum stored beam current in present and future accelerators. It drives inter-bunch and intra-bunch instabilities. Feedback control techniques have been proposed to mitigate transverse instabilities within a bunch as an extension of techniques used to control inter-bunch (coupled-bunch) instabilities. The US LHC Accelerator Research Program (LARP) has supported a collaboration between US labs and CERN to explore systems to mitigate E-cloud instabilities and transverse mode coupled instability (TMCI ) for the SPS and LHC machines. For intra-bunch (within a bunch) control of nanosecond scale bunch lengths the feedback channel has to be wide-band (GHz range) to be able to measure and control the vertical position of individual sections of a bunch. The design and implementation of the feedback control system involves the modeling and identification of the bunch dynamics, the design of a feedback control algorithm, and the selection of digital and analog hardware that operates in the GHz range. We present the goals of this collaboration and analyze the different research lines to implement and evaluate a full-function prototype feedback system for the SPS. We include details of the feedback system topology and technical limitations, modeling and identification of the bunch dynamics via simulators and machine measurements. We estimate the necessary control bandwidths, and complexity of the processing channel via design considerations for the control algorithm. Very initial efforts at modeling feedback control via reduced bunch models and semi-realistic feedback system specifications are presented.
	Slides
DYN02	Simulated Performance of an FIR-Based Feedback System to Control the Electron Cloud Single-Bunch Transverse Instabilities in the CERN SPS	feedback, simulation, controls, electron	56
	R. Secondo, J. Byrd, M. Furman, M. Venturini, J. Vay LBNL J. Fox, C. Rivetta SLAC National Accelerator Laboratory W. Hofle CERN
	The performance of High Energy proton machines like the SPS at CERN is affected by transverse single-bunch instabilities due to the Electron Cloud effect. In a first step to model a Feedback control system to stabilize the bunch dynamics, we use a Finite Impulse Response filter to represent the processing channel. The effect of this simplified processing channel in the bunch dynamics is analyzed using the simulation package WARP-POSINST. We report on simulation results, discuss the basic features of the feedback model and present our plans for further development of the numerical models used in the simulations.
	Slides
PST07	Techniques for Observing Beam Dynamical Effects Caused by the Presence of Electron Clouds	electron, betatron, feedback, dipole	108
	M. Billing, G. Dugan, R. Meller, M. Palmer, G. Ramirez, H. Williams, J. Sikora Cornell University - CLASSE R. Holtzapple California Polytechnic State University
	During the last several years CESR has been studying the effects of electron clouds on stored beams in order to understand their impact on future linear-collider damping ring designs. One of the important issues is the way that the electron cloud alters the dynamics of bunches within the train. Techniques for observing the dynamical effects of beams interacting with the electron clouds have been developed. These methods and examples of measurements are presented here.