SRF2017 - List of Keywords (damping)

Paper	Title	Other Keywords	Page
MOPB004	Design of a RF Quadrupole Resonator for Landau Damping in HL-LHC	ion, cavity, impedance, quadrupole	51
	K. Papke, A. Grudiev CERN, Geneva, Switzerland
	The design and optimization of a quadrupole resonator for transverse Landau damping in the High Luminosity Large Hadron Collider (HL-LHC) is presented. Two different cavity types are considered whose shape is determined by quadrupolar strength, surface peak fields, and beam coupling impedance. The lower order and higher order mode (LOM and HOM) spectra of the optimized cavities are investigated and different approaches for their damping are proposed. Along an example, the required RF power and optimal external quality factor for the input coupler is derived.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB004
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MOPB028	HOM Coupler Design for CEPC Cavities	ion, HOM, cavity, collider	115
	H.J. Zheng, F. Meng, J.Y. Zhai IHEP, Beijing, People's Republic of China
	Funding: This study was supported by National Key Programme for S&T Research and Development (Grant NO.: 2016YFA0400400) In this paper，it will be presented the higher order mode (HOM) coupler design for the Circular Electron-Positron Collider (CEPC) 650 MHz 2-cell cavity. The higher order modes excited by the intense beam bunches must be damped to avoid additional cryogenic loss and multi-bunch instabilities. To keep the beam stable, the impedance budget and the HOM damping requirement are given. A double notch coaxial HOM coupler, which will be mounted on the beam pipe, is planned to extract the HOM power below the cut-off frequency of the beam pipe. This paper summarizes the RF design of the HOM coupler, tolerance analysis, thermal analysis as well as mechanical structures.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB028
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TUPB004	HOM damping with an enlarged beam tube for HEPS 166.6 MHz SC cavities	HOM, ion, cavity, impedance	389
	H.X. Hao, Z.Q. Li, F. Meng, P. Zhang, X.Y. Zhang IHEP, Beijing, People's Republic of China
	The 166.6 MHz superconducting cavities have been proposed for the High Energy Photon Source (HEPS) storage ring, which is initiated by the Institute of High Energy Physics in Beijing. Their higher order modes (HOMs) have to be damped sufficiently in order to limit coupled-bunch instabilities and parasitic mode losses. In order to keep the beam stable, the impedance budget and the HOM damping requirement are given. As one HOM damping option, an enlarged beam tube allows HOMs to propagate and subsequently be absorbed by downstream HOM dampers installed on the inner surface of the beam tube. And the conventional coaxial HOM coupler, which will be mounted on the big beam tube, is planned to extract the HOM power below the cut-off frequency of the beam pipe.
	Poster TUPB004 [1.132 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB004
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TUPB033	Tests of the High Current Slotted Superconducting Cavity with Extremely Low Impedance	cavity, HOM, ion, GUI	451
	Z.C. Liu, J. Gao, F.S. He, S. Jin, Z.H. Mi, T.X. Zhao, H.J. Zheng IHEP, Beijing, People's Republic of China F. Wang, D.H. Zhuang PKU, Beijing, People's Republic of China
	Slotted superconducting cavity is a novel structure with extremely low impedance and high BBU threshold. It can be used in various high current applications. A 1.3 GHz 3-cell slotted superconducting cavity was designed and tested. The room temperature test results show the cavity has an extremely low impedance. The vertical test results show the cavity gradient can reach several MV/m, but it was limited by the test end group made of steel.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB033
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TUPB052	Higher Order Modes Damping in 9-cell Superconducting Cavity with Grooved Beam Pipe	HOM, cavity, ion, quadrupole	502
	A.M. Bulygin, R.V. Donetskiy, Ya.V. Shashkov MEPhI, Moscow, Russia
	This paper is focused on higher order modes (HOM) damping efficiency analysis in 9-cell superconducting cavities with HOM couplers and with grooved beam pipe. Comparison of two methods of HOM damping is presented. In order to increase efficiency of damping of trapped modes the end cells of the structure were modified. Higher order modes, tesla, SRF
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB052
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THPB059	Simulation and Measurements of Crab Cavity HOMs and HOM Couplers for HL-LHC	ion, HOM, cavity, simulation	881
	J.A. Mitchell, T.J. Jones Lancaster University, Lancaster, United Kingdom R. Apsimon, G. Burt, N.C. Shipman Cockcroft Institute, Lancaster University, Lancaster, United Kingdom I. Ben-Zvi, S. Verdú-Andrés, B. P. Xiao BNL, Upton, Long Island, New York, USA R. Calaga, A. Castilla, A. Macpherson, N.C. Shipman, A. Zwozniak CERN, Geneva, Switzerland T. Powers, H. Wang JLab, Newport News, Virginia, USA N.C. Shipman UMAN, Manchester, United Kingdom
	Two Superconducting Radio-Frequency (SRF) crab cavities are foreseen for the High Luminosity LHC (HL-LHC) upgrade. Preliminary beam tests of the Double Quarter Wave (DQW) crab cavity will take place in the Super Proton Synchrotron (SPS) in 2018. For damping of the cavity's Higher Order Modes (HOMs) the DQW has three identical on-cell, superconducting HOM couplers. The couplers are actively cooled by liquid heluim. In this paper, electromagnetic simulations of the HOMs and HOM couplers are presented. A novel approach to pre-installation spectral analysis of the HOM couplers is then presented, detailing both simulated and measured data. Measurements of the cavity HOMs at warm and in Vertical Test Facilities (VTFs) at both JLAB and CERN are detailed, comparing the measured characteristics of each mode to that of the simulated data-sets. Finally, the measured cavity data is compared with the test box measurements to see by what extent any reduction in damping can be predicted.
	Poster THPB059 [8.192 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB059
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MOPB004

Design of a RF Quadrupole Resonator for Landau Damping in HL-LHC

ion, cavity, impedance, quadrupole

51

K. Papke, A. Grudiev
CERN, Geneva, Switzerland

The design and optimization of a quadrupole resonator for transverse Landau damping in the High Luminosity Large Hadron Collider (HL-LHC) is presented. Two different cavity types are considered whose shape is determined by quadrupolar strength, surface peak fields, and beam coupling impedance. The lower order and higher order mode (LOM and HOM) spectra of the optimized cavities are investigated and different approaches for their damping are proposed. Along an example, the required RF power and optimal external quality factor for the input coupler is derived.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB004

Export •

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

MOPB028

HOM Coupler Design for CEPC Cavities

ion, HOM, cavity, collider

115

H.J. Zheng, F. Meng, J.Y. Zhai
IHEP, Beijing, People's Republic of China

Funding: This study was supported by National Key Programme for S&T Research and Development (Grant NO.: 2016YFA0400400)
In this paper，it will be presented the higher order mode (HOM) coupler design for the Circular Electron-Positron Collider (CEPC) 650 MHz 2-cell cavity. The higher order modes excited by the intense beam bunches must be damped to avoid additional cryogenic loss and multi-bunch instabilities. To keep the beam stable, the impedance budget and the HOM damping requirement are given. A double notch coaxial HOM coupler, which will be mounted on the beam pipe, is planned to extract the HOM power below the cut-off frequency of the beam pipe. This paper summarizes the RF design of the HOM coupler, tolerance analysis, thermal analysis as well as mechanical structures.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB028

Export •

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

TUPB004

HOM damping with an enlarged beam tube for HEPS 166.6 MHz SC cavities

HOM, ion, cavity, impedance

389

H.X. Hao, Z.Q. Li, F. Meng, P. Zhang, X.Y. Zhang
IHEP, Beijing, People's Republic of China

The 166.6 MHz superconducting cavities have been proposed for the High Energy Photon Source (HEPS) storage ring, which is initiated by the Institute of High Energy Physics in Beijing. Their higher order modes (HOMs) have to be damped sufficiently in order to limit coupled-bunch instabilities and parasitic mode losses. In order to keep the beam stable, the impedance budget and the HOM damping requirement are given. As one HOM damping option, an enlarged beam tube allows HOMs to propagate and subsequently be absorbed by downstream HOM dampers installed on the inner surface of the beam tube. And the conventional coaxial HOM coupler, which will be mounted on the big beam tube, is planned to extract the HOM power below the cut-off frequency of the beam pipe.

Poster TUPB004 [1.132 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB004

Export •

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

TUPB033

Tests of the High Current Slotted Superconducting Cavity with Extremely Low Impedance

cavity, HOM, ion, GUI

451

Z.C. Liu, J. Gao, F.S. He, S. Jin, Z.H. Mi, T.X. Zhao, H.J. Zheng
IHEP, Beijing, People's Republic of China
F. Wang, D.H. Zhuang
PKU, Beijing, People's Republic of China

Slotted superconducting cavity is a novel structure with extremely low impedance and high BBU threshold. It can be used in various high current applications. A 1.3 GHz 3-cell slotted superconducting cavity was designed and tested. The room temperature test results show the cavity has an extremely low impedance. The vertical test results show the cavity gradient can reach several MV/m, but it was limited by the test end group made of steel.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB033

Export •

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

TUPB052

Higher Order Modes Damping in 9-cell Superconducting Cavity with Grooved Beam Pipe

HOM, cavity, ion, quadrupole

502

A.M. Bulygin, R.V. Donetskiy, Ya.V. Shashkov
MEPhI, Moscow, Russia

This paper is focused on higher order modes (HOM) damping efficiency analysis in 9-cell superconducting cavities with HOM couplers and with grooved beam pipe. Comparison of two methods of HOM damping is presented. In order to increase efficiency of damping of trapped modes the end cells of the structure were modified.
Higher order modes, tesla, SRF

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB052

Export •

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

THPB059

Simulation and Measurements of Crab Cavity HOMs and HOM Couplers for HL-LHC

ion, HOM, cavity, simulation

881

J.A. Mitchell, T.J. Jones
Lancaster University, Lancaster, United Kingdom
R. Apsimon, G. Burt, N.C. Shipman
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
I. Ben-Zvi, S. Verdú-Andrés, B. P. Xiao
BNL, Upton, Long Island, New York, USA
R. Calaga, A. Castilla, A. Macpherson, N.C. Shipman, A. Zwozniak
CERN, Geneva, Switzerland
T. Powers, H. Wang
JLab, Newport News, Virginia, USA
N.C. Shipman
UMAN, Manchester, United Kingdom

Two Superconducting Radio-Frequency (SRF) crab cavities are foreseen for the High Luminosity LHC (HL-LHC) upgrade. Preliminary beam tests of the Double Quarter Wave (DQW) crab cavity will take place in the Super Proton Synchrotron (SPS) in 2018. For damping of the cavity's Higher Order Modes (HOMs) the DQW has three identical on-cell, superconducting HOM couplers. The couplers are actively cooled by liquid heluim. In this paper, electromagnetic simulations of the HOMs and HOM couplers are presented. A novel approach to pre-installation spectral analysis of the HOM couplers is then presented, detailing both simulated and measured data. Measurements of the cavity HOMs at warm and in Vertical Test Facilities (VTFs) at both JLAB and CERN are detailed, comparing the measured characteristics of each mode to that of the simulated data-sets. Finally, the measured cavity data is compared with the test box measurements to see by what extent any reduction in damping can be predicted.

Poster THPB059 [8.192 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB059

Export •

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