IPAC2019 - List of Authors (Li, Z.)

Paper	Title	Page
TUPGW099	Superconducting Crab Cavity Options for Short X-Ray Pulse Generation in SPEAR3	1647
	F. Toufexis, V.A. Dolgashev, X. Huang, Z. Li SLAC, Menlo Park, California, USA
	Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515. We are exploring methods to generate short X-ray pulses in SPEAR3 on the order of 1 ps to enable studying ultrafast processes in materials. We are developing a 2-frequency crab cavity scheme with two sets of crab cavities* at the 6th and 6.5th harmonics of the 476 MHz ring RF frequency. In previous work we studied a normal conducting crab cavity for SPEAR3. In this work we explored two superconducting cavity options: a traditional elliptical cavity and the Quasi-waveguide Resonator. We found that the Quasi-waveguide Resonator cannot meet our field uniformity specifications due to higher order multipole fields. We then optimized a traditional elliptical cavity with the input, Lower Order Modes, and Higher Order Modes couplers following the Argonne Advanced Photon Source design. A. Zholents, et al, Nucl. Instrum. Methods Phys. Res., Sect. A, Vol. 425 (1999), p. 385. Z. Li, et al, Proceedings of IPAC17. * A. Lunin, et al, Proceedings of HOMSC14.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW099
About •	paper received ※ 11 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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TUPRB101	Damping Trapped Modes in an in-Vacuum Undulator at a Synchrotron Radiation Light Source	1895
TUPRB098	use link to see paper's listing under its alternate paper code
	K. Tian, Z. Li, A. Ringwall, J.J. Sebek SLAC, Menlo Park, California, USA
	Funding: Work supported by US Department of Energy Contract DE-AC03-76SF00515. In this paper, we report the efforts in solving the problem of coupled-bunch instabilities caused by an in-vacuum undulator in the SPEAR3 storage ring. After exploring several approaches to reduce the strength of the trapped modes, we found that ferrite dampers were the most effective and simplest way for mode damping in our SPEAR3 in-vacuum undulator. The results of the first RF cold measurement on an in-vacuum undulator equipped with these ferrite dampers agree well with numerical simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB101
About •	paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEPRB077	Simulation and Measurements of HOM Filter of the LARP Prototype RF-Dipole Crabbing Cavity Using an RF Test Box	2999
	S.U. De Silva, J.R. Delayen ODU, Norfolk, Virginia, USA Z. Li SLAC, Menlo Park, California, USA
	The RF-Dipole Crabbing Cavity designed for the LHC High Luminosity Upgrade includes two higher order mode (HOM) couplers. One of the HOM couplers is an rf filter, which is a high pass filter designed to couple to the horizontal dipole modes and accelerating modes up to 2 GHz, while rejecting the fundamental operating mode at 400 MHz. The coupler consists of a high pass filter circuit where the rejection of the operating mode and transmission of HOMs are sensitive to dimensional deviations. An rf test box has been designed to measure the transmission of the rf filter in order to qualify the fabricated HOM coupler and to tune the coupler. This paper presents the measurements of the HOM coupler with the rf test box.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB077
About •	paper received ※ 20 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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WEPRB090	The Design of Parallel-Feed SC RF Accelerator Structure	3024
	M.H. Nasr, Z. Li, S.G. Tantawi, P.B. Welander SLAC, Menlo Park, California, USA
	Funding: Research funded by a SLAC Laboratory-Directed Research and Development award, supported by the U.S. Department of Energy, contract number DE-AC02-76SF00515 Development of superconducting RF (SRF) accelerator technology that enables both higher gradient and higher efficiency is crucial for future machines. While much of the recent R&D focus has been on materials and surface science, our aim is to optimize the cavity geometry to maximize performance with current materials. The recent demonstration of a highly efficient parallel-feed normal-conducting RF structure at SLAC has served as a proof-of-concept. Instead of coupled elliptical cells, the structure employs isolated re-entrant cells. To feed RF power to the cavities, each cell is directly coupled to an integrated manifold. The structure is made in two parts, split along the beam axis, which are then joined. Applied to SRF, simulations suggest such a structure could nearly double the achievable gradient, while reducing cryogenic RF loss by more than half. We are experimentally verifying the concept using an X-band SRF design to be tested at SLAC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB090
About •	paper received ※ 24 May 2019 paper accepted ※ 27 May 2019 issue date ※ 21 June 2019
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WEPRB098	Cryogenic RF Performance of Double-Quarter Wave Cavities Equipped with HOM Filters	3043
	S. Verdú-Andrés, I. Ben-Zvi, Q. Wu, B.P. Xiao BNL, Upton, Long Island, New York, USA I. Ben-Zvi Stony Brook University, Stony Brook, USA G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom G. Burt, J.A. Mitchell Lancaster University, Lancaster, United Kingdom R. Calaga, O. Capatina CERN, Meyrin, Switzerland N.A. Huque, E.A. McEwen, H. Park, T. Powers JLab, Newport News, Virginia, USA Z. Li, A. Ratti SLAC, Menlo Park, California, USA
	Funding: Work supported by US DOE through BSA LLC under contracts No. DE-AC02-98CH10886, No. DE-SC0012704, and the US LHC Accelerator Research Program (LARP) and by the EU HL-LHC Project. Crab cavities are one of the several components included in the luminosity upgrade of the Large Hadron Collider (HL-LHC). The cavities have to provide a nominal deflecting kick of 3.4 MV per cavity while the cryogenic load per cavity stays below 5 W. Cold RF tests confirmed the required performances in bare cavities, with several cavities exceeding the required voltage by more than 50%. However, the first tests of a Double-Quarter Wave (DQW) cavity with one out of three HOM filters did not reach the required voltage. The present paper describes the studies and tests conducted on a DQW cavity with HOM filter to understand the limiting factor. The recipe to meet the performance specification and exceed the voltage requirement by more than 35% is discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB098
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPTS088	Integration of Cavity Design and Beam Dynamics Simulation Using the Parallel IMPACT and the ACE3P Codes	3317
	J. Qiang, D.A. Bizzozero LBNL, Berkeley, California, USA L. Ge, Z. Li, C.-K. Ng, L. Xiao SLAC, Menlo Park, California, USA
	Funding: This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 and DE-AC02-76SF00515, The 3D parallel code suite IMPACT has been extensively used in the beam dynamics study of photoinjectors while the 3D parallel code ACE3P has been extensively used in the RF cavity design. In this paper, we propose integrating the ACE3P cavity design and the IMPACT beam dynamics simulation into a single work flow. Such a workflow enables efficient simulation of 3D effects(e.g. RF coupler) on high performance computers.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS088
About •	paper received ※ 07 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Superconducting Crab Cavity Options for Short X-Ray Pulse Generation in SPEAR3

1647

F. Toufexis, V.A. Dolgashev, X. Huang, Z. Li
SLAC, Menlo Park, California, USA

Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515.
We are exploring methods to generate short X-ray pulses in SPEAR3 on the order of 1 ps to enable studying ultrafast processes in materials. We are developing a 2-frequency crab cavity scheme with two sets of crab cavities* at the 6th and 6.5th harmonics of the 476 MHz ring RF frequency. In previous work we studied a normal conducting crab cavity for SPEAR3**. In this work we explored two superconducting cavity options: a traditional elliptical cavity and the Quasi-waveguide Resonator***. We found that the Quasi-waveguide Resonator cannot meet our field uniformity specifications due to higher order multipole fields. We then optimized a traditional elliptical cavity with the input, Lower Order Modes, and Higher Order Modes couplers following the Argonne Advanced Photon Source design.
* A. Zholents, et al, Nucl. Instrum. Methods Phys. Res., Sect. A, Vol. 425 (1999), p. 385.
** Z. Li, et al, Proceedings of IPAC17.
*** A. Lunin, et al, Proceedings of HOMSC14.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW099

About •

paper received ※ 11 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

Export •

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

TUPRB101

Damping Trapped Modes in an in-Vacuum Undulator at a Synchrotron Radiation Light Source

1895

TUPRB098

use link to see paper's listing under its alternate paper code

K. Tian, Z. Li, A. Ringwall, J.J. Sebek
SLAC, Menlo Park, California, USA

Funding: Work supported by US Department of Energy Contract DE-AC03-76SF00515.
In this paper, we report the efforts in solving the problem of coupled-bunch instabilities caused by an in-vacuum undulator in the SPEAR3 storage ring. After exploring several approaches to reduce the strength of the trapped modes, we found that ferrite dampers were the most effective and simplest way for mode damping in our SPEAR3 in-vacuum undulator. The results of the first RF cold measurement on an in-vacuum undulator equipped with these ferrite dampers agree well with numerical simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB101

About •

paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

Export •

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

WEPRB077

Simulation and Measurements of HOM Filter of the LARP Prototype RF-Dipole Crabbing Cavity Using an RF Test Box

2999

S.U. De Silva, J.R. Delayen
ODU, Norfolk, Virginia, USA
Z. Li
SLAC, Menlo Park, California, USA

The RF-Dipole Crabbing Cavity designed for the LHC High Luminosity Upgrade includes two higher order mode (HOM) couplers. One of the HOM couplers is an rf filter, which is a high pass filter designed to couple to the horizontal dipole modes and accelerating modes up to 2 GHz, while rejecting the fundamental operating mode at 400 MHz. The coupler consists of a high pass filter circuit where the rejection of the operating mode and transmission of HOMs are sensitive to dimensional deviations. An rf test box has been designed to measure the transmission of the rf filter in order to qualify the fabricated HOM coupler and to tune the coupler. This paper presents the measurements of the HOM coupler with the rf test box.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB077

About •

paper received ※ 20 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

Export •

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

WEPRB090

The Design of Parallel-Feed SC RF Accelerator Structure

3024

M.H. Nasr, Z. Li, S.G. Tantawi, P.B. Welander
SLAC, Menlo Park, California, USA

Funding: Research funded by a SLAC Laboratory-Directed Research and Development award, supported by the U.S. Department of Energy, contract number DE-AC02-76SF00515
Development of superconducting RF (SRF) accelerator technology that enables both higher gradient and higher efficiency is crucial for future machines. While much of the recent R&D focus has been on materials and surface science, our aim is to optimize the cavity geometry to maximize performance with current materials. The recent demonstration of a highly efficient parallel-feed normal-conducting RF structure at SLAC has served as a proof-of-concept. Instead of coupled elliptical cells, the structure employs isolated re-entrant cells. To feed RF power to the cavities, each cell is directly coupled to an integrated manifold. The structure is made in two parts, split along the beam axis, which are then joined. Applied to SRF, simulations suggest such a structure could nearly double the achievable gradient, while reducing cryogenic RF loss by more than half. We are experimentally verifying the concept using an X-band SRF design to be tested at SLAC.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB090

About •

paper received ※ 24 May 2019 paper accepted ※ 27 May 2019 issue date ※ 21 June 2019

Export •

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

WEPRB098

Cryogenic RF Performance of Double-Quarter Wave Cavities Equipped with HOM Filters

3043

S. Verdú-Andrés, I. Ben-Zvi, Q. Wu, B.P. Xiao
BNL, Upton, Long Island, New York, USA
I. Ben-Zvi
Stony Brook University, Stony Brook, USA
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
G. Burt, J.A. Mitchell
Lancaster University, Lancaster, United Kingdom
R. Calaga, O. Capatina
CERN, Meyrin, Switzerland
N.A. Huque, E.A. McEwen, H. Park, T. Powers
JLab, Newport News, Virginia, USA
Z. Li, A. Ratti
SLAC, Menlo Park, California, USA

Funding: Work supported by US DOE through BSA LLC under contracts No. DE-AC02-98CH10886, No. DE-SC0012704, and the US LHC Accelerator Research Program (LARP) and by the EU HL-LHC Project.
Crab cavities are one of the several components included in the luminosity upgrade of the Large Hadron Collider (HL-LHC). The cavities have to provide a nominal deflecting kick of 3.4 MV per cavity while the cryogenic load per cavity stays below 5 W. Cold RF tests confirmed the required performances in bare cavities, with several cavities exceeding the required voltage by more than 50%. However, the first tests of a Double-Quarter Wave (DQW) cavity with one out of three HOM filters did not reach the required voltage. The present paper describes the studies and tests conducted on a DQW cavity with HOM filter to understand the limiting factor. The recipe to meet the performance specification and exceed the voltage requirement by more than 35% is discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB098

About •

paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

Export •

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

WEPTS088

Integration of Cavity Design and Beam Dynamics Simulation Using the Parallel IMPACT and the ACE3P Codes

3317

J. Qiang, D.A. Bizzozero
LBNL, Berkeley, California, USA
L. Ge, Z. Li, C.-K. Ng, L. Xiao
SLAC, Menlo Park, California, USA

Funding: This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 and DE-AC02-76SF00515,
The 3D parallel code suite IMPACT has been extensively used in the beam dynamics study of photoinjectors while the 3D parallel code ACE3P has been extensively used in the RF cavity design. In this paper, we propose integrating the ACE3P cavity design and the IMPACT beam dynamics simulation into a single work flow. Such a workflow enables efficient simulation of 3D effects(e.g. RF coupler) on high performance computers.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS088

About •

paper received ※ 07 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

Export •

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