IPAC2017 - List of Authors (De Santis, S.)

Paper	Title	Page
TUPAB121	Bench Measurements and Beam Tests of a Prototype Stripline Kicker for Swap-Out Injection in the ALS-U	1599
	S. De Santis, J.M. Byrd, T.H. Luo, G.C. Pappas, C. Steier, C.A. Swenson, W.L. Waldron LBNL, Berkeley, California, USA
	Funding: Work supported by the the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The ALS upgrade to a diffraction-limited light source (ALS-U Project) relies on a swap-out injection scheme, where the circulating current is maintained constant by injecting on-axis fresh bunch trains, replacing old trains, which are simultaneously extracted. The realization of a stripline kicker to perform such an operation presents several challenges in terms of optimal matching to the pulser, contributions to the beam coupling impedance, and dissipation of the power deposited by the stored beam. To test our design choices for the ALS-U kicker, we have built and installed on the ALS a kicker with characteristics similar to the design for the ALS-U, as the more challenging aspects of the project are concerned. In particular, while the small distance between stripline electrodes reduces the required pulser voltage, the extreme proximity of the circulating beam requires a careful evaluation of the interaction between beam and kicker. In this paper we present the first measurements with beam, after the test kicker installation, together with the results of bench measurements performed on a cold model and computer simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB121
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TUPIK119	Control of Intra-Bunch Vertical Instabilities at the SPS - Measurements and Technology Demonstration	2005
	J.D. Fox, J.E. Dusatko, C.H. Rivetta, O. Turgut SLAC, Menlo Park, California, USA H. Bartosik, W. Höfle, K.S.B. Li, E. Métral, B. Salvant, U. Wehrle CERN, Geneva, Switzerland S. De Santis LBNL, Berkeley, California, USA
	Funding: Work supported by the U.S. Department of Energy under contract # DOE-AC02-76SF00515, the US LHC Accelerator Research Program ( LARP), the FP7 High Luminosity LHC Project and the US-Japan Cooperative Program in High Energy Physics We present recent measurements demonstrating control of unstable beam motion in single bunch and bunch train configurations at the SPS. The work is motivated by anticipated intensity increases from the LIU and HL-LHC upgrade programs, and has included the development of a GHz bandwidth reconfigurable 4 GS/S signal processor with wideband kickers and associated amplifiers. The system was operated at 3.2GS/s with 16 samples across a 5 ns RF bucket (4.2 ns bunch at injection). The experimental results confirm damping of intra-bunch instabilities in both Q20 and Q26 optics configurations for intensities of 2x10¹¹ P/bunch. Instabilities with growth times of 200 turns are well-controlled from injection, consistent with the achievable gains for the 2 installed stripline kickers with 1 kW broadband power. Measurements from multiple studies in single-bunch and bunch train configurations show achieved damping rates, control of multiple intra-bunch modes, behavior of the system at injection and final damped noise floor. We present an analysis method to study the relative phase of slice motion during a transient to discriminate between TMCI and other types of Head-Tail instabilities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK119
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WEPAB103	On-Axis Swap-Out Injection R+D for ALS-U	2821
	C. Steier, A. Anders, S. De Santis, T.H. Luo, T. Oliver, G.C. Pappas, C. Sun, C.A. Swenson, W.L. Waldron LBNL, Berkeley, California, USA
	Funding: This work is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The ALS-U upgrade promises to deliver diffraction limited performance throughout the soft x-ray range by lowering the horizontal emittance by a factor of 40 compared to the current ALS. One of the consequences of producing a small emittance is a small dynamic aperture, although the momentum acceptance will remain large enough for acceptable beam lifetime. To overcome this challenge, ALS-U will use on-axis swap-out injection to exchange bunch trains between the storage ring and an accumulator ring. On-axis swapout injection requires special fast pulsers and state-of-the-art stripline kicker magnets. This paper reports on the results of the on-axis swap-out injection R&D program, including beam tests of a complete stripline kicker/pulser system on the current ALS and the development of methods to speed up beam based commissioning after the upgrade shutdown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB103
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WEPAB104	Status of the Conceptual Design of ALS-U	2824
	C. Steier, A.P. Allézy, A. Anders, K.M. Baptiste, J.M. Byrd, K. Chow, G.D. Cutler, S. De Santis, R.J. Donahue, R.M. Duarte, J.-Y. Jung, S.C. Leemann, M. Leitner, T.H. Luo, H. Nishimura, T. Oliver, O. Omolayo, J.R. Osborn, G.C. Pappas, S. Persichelli, M. Placidi, G.J. Portmann, S. Reyes, D. Robin, F. Sannibale, C. Sun, C.A. Swenson, M. Venturini, W.L. Waldron, E.J. Wallén, W. Wan LBNL, Berkeley, California, USA
	Funding: This work is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The ALS-U upgrade promises to deliver diffraction limited performance throughout the soft x-ray range by lowering the horizontal emittance to about 50~pm resulting in 2-3 orders of brightness increase for soft x-rays compared to the current ALS. The design utilizes a multi bend achromat lattice with on-axis swap-out injection and an accumulator ring. One central design goal is to install and commission ALS-U within a short dark period. This paper summarizes the status of the conceptual design of the accelerator, as well as some results of the R&D program that has been ongoing for the last 3 years.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB104
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WEPIK106	Impedance and Collective Effects for the Advanced Light Source Upgrade at LBNL	3192
	S. Persichelli, J.M. Byrd, S. De Santis, D. Li, T.H. Luo, C. Steier, M. Venturini LBNL, Berkeley, California, USA
	Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 The upgrade of the Advanced Light Source (ALS-U) consists of a multiband achromat ultralow emittance lattice for the production of diffraction-limited soft x-rays. A very important issue for ALS-U is represented by instabilities induced by wakefields, that may limit the peak current of individual bunches and the total beam current. In addition, vacuum chamber apertures of few millimeters, that are a key feature of low-emittance machines, can result in a significant increase in the Resistive Wall (RW) impedance. In this paper we present progress on establishing short range wakefield model for ALS-U and evaluating the impact on the longitudinal and transverse single-bunch dynamics.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK106
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Paper

Title

Page

Bench Measurements and Beam Tests of a Prototype Stripline Kicker for Swap-Out Injection in the ALS-U

1599

S. De Santis, J.M. Byrd, T.H. Luo, G.C. Pappas, C. Steier, C.A. Swenson, W.L. Waldron
LBNL, Berkeley, California, USA

Funding: Work supported by the the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The ALS upgrade to a diffraction-limited light source (ALS-U Project) relies on a swap-out injection scheme, where the circulating current is maintained constant by injecting on-axis fresh bunch trains, replacing old trains, which are simultaneously extracted. The realization of a stripline kicker to perform such an operation presents several challenges in terms of optimal matching to the pulser, contributions to the beam coupling impedance, and dissipation of the power deposited by the stored beam. To test our design choices for the ALS-U kicker, we have built and installed on the ALS a kicker with characteristics similar to the design for the ALS-U, as the more challenging aspects of the project are concerned. In particular, while the small distance between stripline electrodes reduces the required pulser voltage, the extreme proximity of the circulating beam requires a careful evaluation of the interaction between beam and kicker. In this paper we present the first measurements with beam, after the test kicker installation, together with the results of bench measurements performed on a cold model and computer simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB121

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

TUPIK119

Control of Intra-Bunch Vertical Instabilities at the SPS - Measurements and Technology Demonstration

2005

J.D. Fox, J.E. Dusatko, C.H. Rivetta, O. Turgut
SLAC, Menlo Park, California, USA
H. Bartosik, W. Höfle, K.S.B. Li, E. Métral, B. Salvant, U. Wehrle
CERN, Geneva, Switzerland
S. De Santis
LBNL, Berkeley, California, USA

Funding: Work supported by the U.S. Department of Energy under contract # DOE-AC02-76SF00515, the US LHC Accelerator Research Program ( LARP), the FP7 High Luminosity LHC Project and the US-Japan Cooperative Program in High Energy Physics
We present recent measurements demonstrating control of unstable beam motion in single bunch and bunch train configurations at the SPS. The work is motivated by anticipated intensity increases from the LIU and HL-LHC upgrade programs, and has included the development of a GHz bandwidth reconfigurable 4 GS/S signal processor with wideband kickers and associated amplifiers. The system was operated at 3.2GS/s with 16 samples across a 5 ns RF bucket (4.2 ns bunch at injection). The experimental results confirm damping of intra-bunch instabilities in both Q20 and Q26 optics configurations for intensities of 2x10¹¹ P/bunch. Instabilities with growth times of 200 turns are well-controlled from injection, consistent with the achievable gains for the 2 installed stripline kickers with 1 kW broadband power. Measurements from multiple studies in single-bunch and bunch train configurations show achieved damping rates, control of multiple intra-bunch modes, behavior of the system at injection and final damped noise floor. We present an analysis method to study the relative phase of slice motion during a transient to discriminate between TMCI and other types of Head-Tail instabilities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK119

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

WEPAB103

On-Axis Swap-Out Injection R+D for ALS-U

2821

C. Steier, A. Anders, S. De Santis, T.H. Luo, T. Oliver, G.C. Pappas, C. Sun, C.A. Swenson, W.L. Waldron
LBNL, Berkeley, California, USA

Funding: This work is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The ALS-U upgrade promises to deliver diffraction limited performance throughout the soft x-ray range by lowering the horizontal emittance by a factor of 40 compared to the current ALS. One of the consequences of producing a small emittance is a small dynamic aperture, although the momentum acceptance will remain large enough for acceptable beam lifetime. To overcome this challenge, ALS-U will use on-axis swap-out injection to exchange bunch trains between the storage ring and an accumulator ring. On-axis swapout injection requires special fast pulsers and state-of-the-art stripline kicker magnets. This paper reports on the results of the on-axis swap-out injection R&D program, including beam tests of a complete stripline kicker/pulser system on the current ALS and the development of methods to speed up beam based commissioning after the upgrade shutdown.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB103

Export •

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

WEPAB104

Status of the Conceptual Design of ALS-U

2824

C. Steier, A.P. Allézy, A. Anders, K.M. Baptiste, J.M. Byrd, K. Chow, G.D. Cutler, S. De Santis, R.J. Donahue, R.M. Duarte, J.-Y. Jung, S.C. Leemann, M. Leitner, T.H. Luo, H. Nishimura, T. Oliver, O. Omolayo, J.R. Osborn, G.C. Pappas, S. Persichelli, M. Placidi, G.J. Portmann, S. Reyes, D. Robin, F. Sannibale, C. Sun, C.A. Swenson, M. Venturini, W.L. Waldron, E.J. Wallén, W. Wan
LBNL, Berkeley, California, USA

Funding: This work is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The ALS-U upgrade promises to deliver diffraction limited performance throughout the soft x-ray range by lowering the horizontal emittance to about 50~pm resulting in 2-3 orders of brightness increase for soft x-rays compared to the current ALS. The design utilizes a multi bend achromat lattice with on-axis swap-out injection and an accumulator ring. One central design goal is to install and commission ALS-U within a short dark period. This paper summarizes the status of the conceptual design of the accelerator, as well as some results of the R&D program that has been ongoing for the last 3 years.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB104

Export •

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

WEPIK106

Impedance and Collective Effects for the Advanced Light Source Upgrade at LBNL

3192

S. Persichelli, J.M. Byrd, S. De Santis, D. Li, T.H. Luo, C. Steier, M. Venturini
LBNL, Berkeley, California, USA

Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231
The upgrade of the Advanced Light Source (ALS-U) consists of a multiband achromat ultralow emittance lattice for the production of diffraction-limited soft x-rays. A very important issue for ALS-U is represented by instabilities induced by wakefields, that may limit the peak current of individual bunches and the total beam current. In addition, vacuum chamber apertures of few millimeters, that are a key feature of low-emittance machines, can result in a significant increase in the Resistive Wall (RW) impedance. In this paper we present progress on establishing short range wakefield model for ALS-U and evaluating the impact on the longitudinal and transverse single-bunch dynamics.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK106

Export •

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