PAC2013 - List of Authors (Eddy, N.)

Paper	Title	Page
THPAC20	Beam Position and Phase Measurements of Microampere Beams at the Michigan State University ReA3 Facility	1187
	J.L. Crisp, B. Durickovic, G. Kiupel, D. Leitner, J.A. Rodriguez, T. Russo, R.C. Webber, W. Wittmer FRIB, East Lansing, Michigan, USA C.I. Briegel, N. Eddy, B.J. Fellenz, D. Slimmer Fermilab, Batavia, USA D. Constan-Wahl, S.W. Krause, S. Nash NSCL, East Lansing, Michigan, USA M. Wendt CERN, Geneva, Switzerland
	A high power CW, heavy ion linac will be the driver accelerator for the Facility for Rare Isotope Beams being designed at Michigan State University. The linac requires a Beam Position Monitoring (BPM) system with better than 100 micron resolution at 100 microamperes beam current. A low beam current test of the candidate technology, button pick-ups and direct digital down-conversion signal processing, was conducted in the ReA3 re-accelerated beam facility at MSU. The test is described. Beam position and phase measurement results, demonstrating ~200 micron and ~1 degree resolution in a 90 kHz bandwidth for a 0.5 microampere beam current, are reported.

THPHO23	Improvement of Digital Filter for the FNAL Booster Transverse Dampers	1349
	T.V. Zolkin University of Chicago, Chicago, Illinois, USA N. Eddy, V.A. Lebedev Fermilab, Batavia, USA
	Fermilab Booster has a transverse damping system which independently suppresses beam instabilities in the horizontal and vertical planes. A suppression of the common mode signal is achieved by digital notch filter which is based on subtracting beam positions for two consecutive turns. Such system operates well if the orbit position changes sufficiently slow. Unfortunately it is not the case for Fermilab Booster where the entire accelerating cycle consists of about 20,000 turns and successful transition crossing requires the orbit drifts up to about 10 um/turn resulting in excessive power, power amplifier saturation and loss of stability. To suppress this effect we suggest an improvement to the digital filter which can take into account fast orbit changes by using bunch positions of a few previous turns. To take into account the orbit change up to N-th order polynomial in time the system requires (N + 3) turns of "prehistory". In the case of sufficiently small gain the damping rate and the optimal digital filter coefficients are obtained analytically. Numerical simulations verify analytical theory for the small gain and predict a system performance with gain increase.

Paper

Title

Page

Beam Position and Phase Measurements of Microampere Beams at the Michigan State University ReA3 Facility

1187

J.L. Crisp, B. Durickovic, G. Kiupel, D. Leitner, J.A. Rodriguez, T. Russo, R.C. Webber, W. Wittmer
FRIB, East Lansing, Michigan, USA
C.I. Briegel, N. Eddy, B.J. Fellenz, D. Slimmer
Fermilab, Batavia, USA
D. Constan-Wahl, S.W. Krause, S. Nash
NSCL, East Lansing, Michigan, USA
M. Wendt
CERN, Geneva, Switzerland

A high power CW, heavy ion linac will be the driver accelerator for the Facility for Rare Isotope Beams being designed at Michigan State University. The linac requires a Beam Position Monitoring (BPM) system with better than 100 micron resolution at 100 microamperes beam current. A low beam current test of the candidate technology, button pick-ups and direct digital down-conversion signal processing, was conducted in the ReA3 re-accelerated beam facility at MSU. The test is described. Beam position and phase measurement results, demonstrating ~200 micron and ~1 degree resolution in a 90 kHz bandwidth for a 0.5 microampere beam current, are reported.

THPHO23

Improvement of Digital Filter for the FNAL Booster Transverse Dampers

1349

T.V. Zolkin
University of Chicago, Chicago, Illinois, USA
N. Eddy, V.A. Lebedev
Fermilab, Batavia, USA

Fermilab Booster has a transverse damping system which independently suppresses beam instabilities in the horizontal and vertical planes. A suppression of the common mode signal is achieved by digital notch filter which is based on subtracting beam positions for two consecutive turns. Such system operates well if the orbit position changes sufficiently slow. Unfortunately it is not the case for Fermilab Booster where the entire accelerating cycle consists of about 20,000 turns and successful transition crossing requires the orbit drifts up to about 10 um/turn resulting in excessive power, power amplifier saturation and loss of stability. To suppress this effect we suggest an improvement to the digital filter which can take into account fast orbit changes by using bunch positions of a few previous turns. To take into account the orbit change up to N-th order polynomial in time the system requires (N + 3) turns of "prehistory". In the case of sufficiently small gain the damping rate and the optimal digital filter coefficients are obtained analytically. Numerical simulations verify analytical theory for the small gain and predict a system performance with gain increase.