damping

Paper	Title	Other Keywords	Page
WEPSB026	Digital Longitudinal Feedback Systems in Synchrotrons	feedback, synchrotron, acceleration, kicker	224
	V. Zhabitsky JINR, Dubna, Moscow Region
	The stability of a beam in synchrotrons with a digital longitudinal feedback system is treated. A longitudinal feedback system is required in synchrotrons to stabilize the high intensity beams against longitudinal instabilities and to damp the phase injection errors of a bunch. Damping rates of the digital longitudinal feedback system in dependence of its gain and delay are analysed.
WEPSB032	Transverse Feedbacks in the U70 Proton Synchrotron of IHEP	feedback, kicker, pick-up, controls	239
	O. P. Lebedev, N. A. Ignashin, S. V. Ivanov, S. E. Sytov IHEP Protvino, Protvino, Moscow Region
	To handle the adverse effect of transverse injection errors and resistive-wall instability in the U70, two frequency-band-separated feedback circuits are routinely employed. The first one is a narrow-band (around base-band DC) local end-to-end-analog circuit terminated by an electrostatic kicker. The second is a wide-band band-pass circuit with a variable (–10% ca) digital delay line and low-level DSP units and an electro-magnetic kicker. Both the circuits were subjected to a deep renovation during the recent 5 years, which provided a better control over transverse motion of the beam. The paper reports on technical solutions implemented, problem-oriented R&D studies, and beam observations.
THCHX01	Beam Tests of the LHC Transverse Feedback System	feedback, kicker, pick-up, injection	275
	V. Zhabitsky JINR, Dubna, Moscow Region W. Höfle, G. Kotzian, E. Montesinos, M. Schokker, D. Valuch CERN, Geneva
	A powerful transverse feedback system ("LHC Damper") has been installed in LHC in order to stabilise the high intensity beams against coupled bunch transverse instabilities in a frequency range from 3 kHz to 20 MHz and at the same time to damp injection oscillations originating from steering errors and injection kicker ripple. The LHC Damper has been also used for exciting transverse oscillations for the purposes of abort gap cleaning and tune measurement. The LHC Damper includes 4 feedback systems on 2 circulating beams (in other words one feedback system per beam and plane). Every feedback system consists of 4 electrostatic kickers, 4 push-pull wide band power amplifiers, 8 preamplifiers, two digital processing units and 2 beam position monitors with low-level electronics. The power and low-level subsystem layout is described along with first results from the beam commissioning of 16 power amplifiers and 16 electrostatic kickers located in the LHC tunnel. Results of beam tests of the power and low-level subsystems are summarized.
	Slides