controls

Paper	Title	Other Keywords	Page
DYN00	Feedback Control of SPS E-clouds / Transverse Mode Coupled Instabilities	feedback, kicker, 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	kicker, feedback, simulation, 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
PST02	Bunch-By-Bunch Instrumentation Upgrades For CESR, Based On Requirements For The CESR Test Accelerator Research Program	instrumentation, optics, damping, monitoring	88
	N. Rider, J. Alexander, M. Billing, C. Conolly, N. Eggert, E. Fontes, W. Hopkins, B. Kreis, A. Lyndaker, R. Meller, M. Palmer, D. Peterson, M. Rendina, P. Revesz, D. Rubin, J. Savino, R. Seeley, J. Shanks, C. Strohman Cornell University - CLASSE R. Holtzapple California Polytechnic State University J. Flanagan KEK
	The research focus of the CESR Test Accelerator program requires new instrumentation hardware, software and techniques in order to accurately investigate beam dynamics in the presence of electron cloud effects. These new instruments are also required to develop low emittance beam conditions which are key to the success of the damping ring design for the International Linear Collider. This poster will detail some of the architecture and tools which have been developed to support these efforts. Emphasis will be placed on the 4 nS bunch by bunch Beam Position Monitoring system as well as the 4 nS capable X-ray Beam Size Monitor.
PST06	Effects of Reflections on TE-Wave Measurements of Electron Cloud Density	simulation, electron, plasma, background	103
	K. Sonnad, J. Sikora Cornell University - CLASSE K. Hammond Harvard University S. Veitzer Tech-X Corporation
	The simulation code VORPAL has been used as a tool to study charecteristics of TE wave transmission in the presence of electron clouds for CesrTA. We look at how the electron cloud induced phase shift is influenced by (1) reflections of the wave, caused by possible protrusions in the beam pipe and (2)effect of nonuniformities of the cloud density distribution in the transverse plane.
PST12	In Situ SEY Measurements at CesrTA	electron, gun, vacuum, radiation	140
	J. Kim, J. Conway, S. Greenwald, Y. Li, T. Moore, M. Palmer, V. Medjidzade, D. Asner, C. Strohman Cornell University - CLASSE
	Measuring secondary electron yields (SEYs) on technical surfaces in accelerator vacuum systems provides essential information for many accelerator R&D projects, such as the ILC Damping Rings, regarding to electron cloud growth and suppression. As a part of CesrTA research program, we developed and deployed SEY in-situ measurement systems. Two such SEY systems were installed to expose samples with direct and scattered synchrotron radiation (SR), and the SEYs of the samples were measured as a function of SR dosages. In this poster, we describe the in-situ SEY measurement systems and the initial results on bare aluminum and TiN-coated aluminum samples.