IPAC2014 - List of Authors (Rivetta, C.H.)

Paper	Title	Page
TUPRI085	Development of a 4 GS/s Intra-bunch Instability Control System for the SPS - Next Steps	1766
	J.D. Fox, J.M. Cesaratto, J.E. Dusatko, K.M. Pollock, C.H. Rivetta, O. Turgut SLAC, Menlo Park, California, USA S. De Santis LBNL, Berkeley, California, USA W. Höfle, G. Kotzian, U. Wehrle CERN, Geneva, Switzerland
	Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP). We present the expanded system architecture in development for the control of intra-bunch instabilities in the SPS. Earlier efforts concentrated on validating the performance of a single-bunch demonstration processor. This minimal system was successfully commissioned at the SPS just prior to the LS1 shutdown. The architecture is now in expansion for more complex functionality, specifically multi-bunch control, control during energy ramps, and the expansion of the system front-end dynamic range with more sophisticated orbit offset techniques. Two designs of wideband kicker are being developed for installation and evaluation with the beam. With these GHz bandwidth devices and new RF amplifiers we anticipate being able to excite and control internal motion of the beam consistent with modes expected for Ecloud and TMCI effects. We highlight the expanded features, and present strategies for verifying the behavior of the beam-feedback system in the next series of machine measurements planned after the LS1 shutdown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI085
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TUPRI086	Feedback System Design Techniques for Control of Intra-bunch Instabilities at the SPS	1769
	C.H. Rivetta, J.M. Cesaratto, J.E. Dusatko, J.D. Fox, O. Turgut SLAC, Menlo Park, California, USA W. Höfle, G. Kotzian, K.S.B. Li CERN, Geneva, Switzerland
	Funding: Work supported by the U.S. Department of Energy under contract # DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP). The feedback control of intra-bunch instabilities driven by electron-clouds or strong head-tail coupling requires bandwidth sufficient to sense the vertical position and apply multiple corrections within a nanosecond-scale bunch. These requirements impose challenges and limits in the design and implementation of the feedback system. This paper presents model-based design techniques for feedback systems to address the stabilization of the transverse bunch dynamics. These techniques include in the design the effect of noise and signals perturbing the bunch motion. Different controllers are compared based on stability margins and equivalent noise gain between input-output of the processing channel. The controller design uses as example the bunch dynamics defined by the SPS ring including the Q20 optics.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI086
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TUPRI087	A Wideband Slotted Kicker Design for SPS Transverse Intra-bunch Feedback	1772
	J.M. Cesaratto, J.D. Fox, C.H. Rivetta SLAC, Menlo Park, California, USA D. Alesini, A. Gallo, M. Zobov INFN/LNF, Frascati (Roma), Italy S. De Santis LBNL, Berkeley, California, USA W. Höfle CERN, Geneva, Switzerland
	Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP) and by the EU FP7 HiLumi LHC - Grant Agreement 284404. In order for the SPS to meet the beam intensity demands for the HL-LHC upgrade, control and mitigation of transverse beam instabilities caused by electron cloud and TMCI will be essential. For this purpose a wideband intra-bunch feedback method has been proposed, based on a 4 GS/s front end data acquisition and processing, and on a back end frequency response extending to at least 1 GHz. A slotted type kicker, similar to those used for stochastic cooling, as well as an array of stripline kickers have been considered as the terminal elements of the feedback system. A slotted TEM type kicker has been designed fulfilling the bandwidth and kick strength requirements for the SPS application. In this paper we present an updated version of the design and electromagnetic characteristics, leading into the mechanical design and construction of the kicker occurring later this year.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI087
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WEPRI067	Multi-Physics Analysis of CW Superconducting Cavity for the LCLS-II using ACE3P	2645
	Z. Li, C. Adolphsen, O. Kononenko, T.O. Raubenheimer, C.H. Rivetta, M.C. Ross, L. Xiao SLAC, Menlo Park, California, USA
	Funding: Work was supported by the U.S. DOE contract DE-AC02-76SF00515 and used the resources of NERSC at LBNL under US DOE Contract No. DE-AC03-76SF00098. The LCLS-II linac utilizes superconducting technology operating at continuous wave to accelerate the 1-MHz electron beams to 4 GeV to produce tunable FELs. The TESLA 9-cell superconducting cavity is adopted as the baseline design for the linac. The design gradient is approximately 16 MV/m. The highest operating current is 300 μA. Assuming that the RF power is matched at the highest current, the optimal loaded QL of the cavity is found to be around 4·10⁷. Because of the high QL, the cavity bandwidth approaches the background microphonic detuning, and the performance of the cavity is tightly coupled to the mechanical perturbations of the cavity/cryomodule system. The resulting large phase and amplitude variations in the cavity require active feedback to achieve the 0.01% amplitude and phase stability requirements. To understand the cavity RF response and feedback requirements to the microphonics and Lorentz Force detuning, we have developed a simulation model of the RF-mechanical coupled system using parameters obtained with the multi-physics solver ACE3P. We will present the simulation results of the LCLS-II linac under different power feed scenarios and feedback schemes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI067
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Paper

Title

Page

Development of a 4 GS/s Intra-bunch Instability Control System for the SPS - Next Steps

1766

J.D. Fox, J.M. Cesaratto, J.E. Dusatko, K.M. Pollock, C.H. Rivetta, O. Turgut
SLAC, Menlo Park, California, USA
S. De Santis
LBNL, Berkeley, California, USA
W. Höfle, G. Kotzian, U. Wehrle
CERN, Geneva, Switzerland

Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP).
We present the expanded system architecture in development for the control of intra-bunch instabilities in the SPS. Earlier efforts concentrated on validating the performance of a single-bunch demonstration processor. This minimal system was successfully commissioned at the SPS just prior to the LS1 shutdown. The architecture is now in expansion for more complex functionality, specifically multi-bunch control, control during energy ramps, and the expansion of the system front-end dynamic range with more sophisticated orbit offset techniques. Two designs of wideband kicker are being developed for installation and evaluation with the beam. With these GHz bandwidth devices and new RF amplifiers we anticipate being able to excite and control internal motion of the beam consistent with modes expected for Ecloud and TMCI effects. We highlight the expanded features, and present strategies for verifying the behavior of the beam-feedback system in the next series of machine measurements planned after the LS1 shutdown.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI085

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPRI086

Feedback System Design Techniques for Control of Intra-bunch Instabilities at the SPS

1769

C.H. Rivetta, J.M. Cesaratto, J.E. Dusatko, J.D. Fox, O. Turgut
SLAC, Menlo Park, California, USA
W. Höfle, G. Kotzian, K.S.B. Li
CERN, Geneva, Switzerland

Funding: Work supported by the U.S. Department of Energy under contract # DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP).
The feedback control of intra-bunch instabilities driven by electron-clouds or strong head-tail coupling requires bandwidth sufficient to sense the vertical position and apply multiple corrections within a nanosecond-scale bunch. These requirements impose challenges and limits in the design and implementation of the feedback system. This paper presents model-based design techniques for feedback systems to address the stabilization of the transverse bunch dynamics. These techniques include in the design the effect of noise and signals perturbing the bunch motion. Different controllers are compared based on stability margins and equivalent noise gain between input-output of the processing channel. The controller design uses as example the bunch dynamics defined by the SPS ring including the Q20 optics.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI086

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPRI087

A Wideband Slotted Kicker Design for SPS Transverse Intra-bunch Feedback

1772

J.M. Cesaratto, J.D. Fox, C.H. Rivetta
SLAC, Menlo Park, California, USA
D. Alesini, A. Gallo, M. Zobov
INFN/LNF, Frascati (Roma), Italy
S. De Santis
LBNL, Berkeley, California, USA
W. Höfle
CERN, Geneva, Switzerland

Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP) and by the EU FP7 HiLumi LHC - Grant Agreement 284404.
In order for the SPS to meet the beam intensity demands for the HL-LHC upgrade, control and mitigation of transverse beam instabilities caused by electron cloud and TMCI will be essential. For this purpose a wideband intra-bunch feedback method has been proposed, based on a 4 GS/s front end data acquisition and processing, and on a back end frequency response extending to at least 1 GHz. A slotted type kicker, similar to those used for stochastic cooling, as well as an array of stripline kickers have been considered as the terminal elements of the feedback system. A slotted TEM type kicker has been designed fulfilling the bandwidth and kick strength requirements for the SPS application. In this paper we present an updated version of the design and electromagnetic characteristics, leading into the mechanical design and construction of the kicker occurring later this year.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI087

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPRI067

Multi-Physics Analysis of CW Superconducting Cavity for the LCLS-II using ACE3P

2645

Z. Li, C. Adolphsen, O. Kononenko, T.O. Raubenheimer, C.H. Rivetta, M.C. Ross, L. Xiao
SLAC, Menlo Park, California, USA

Funding: Work was supported by the U.S. DOE contract DE-AC02-76SF00515 and used the resources of NERSC at LBNL under US DOE Contract No. DE-AC03-76SF00098.
The LCLS-II linac utilizes superconducting technology operating at continuous wave to accelerate the 1-MHz electron beams to 4 GeV to produce tunable FELs. The TESLA 9-cell superconducting cavity is adopted as the baseline design for the linac. The design gradient is approximately 16 MV/m. The highest operating current is 300 μA. Assuming that the RF power is matched at the highest current, the optimal loaded QL of the cavity is found to be around 4·10⁷. Because of the high QL, the cavity bandwidth approaches the background microphonic detuning, and the performance of the cavity is tightly coupled to the mechanical perturbations of the cavity/cryomodule system. The resulting large phase and amplitude variations in the cavity require active feedback to achieve the 0.01% amplitude and phase stability requirements. To understand the cavity RF response and feedback requirements to the microphonics and Lorentz Force detuning, we have developed a simulation model of the RF-mechanical coupled system using parameters obtained with the multi-physics solver ACE3P. We will present the simulation results of the LCLS-II linac under different power feed scenarios and feedback schemes.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI067

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)