IPAC2015 - List of Keywords (higher-order-mode)

Paper	Title	Other Keywords	Page
MOPWA032	Aspects of SRF Cavity Optimization for BESSY-VSR Upgrade	cavity, HOM, SRF, storage-ring	171
	T. Galek, K. Brackebusch, T. Flisgen, J. Heller, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany B.D. Isbarn, B. Riemann, M. Sommer, T. Weis DELTA, Dortmund, Germany
	Funding: Work supported by Federal Ministry for Research and Education BMBF under contract 05K13HR1. In this work we present a preliminary study of a long chain of cavities and some aspects involved in the optimization procedure. It is important to numerically model and optimize the SRF cavities with respect to external quality factors of the most dangerous higher order modes. BESSY-VSR is an upgrade scheme for the existing BESSY II storage ring aiming to simultaneously support variable electron pulse lengths. Currently, BESSY II supports long 15 ps bunches in the standard user optics configuration and short 1.5 ps bunches in a so-called low-α optics mode. In order to develop BESSY II into a variable electron pulse length storage ring, additional two sets of SRF higher-harmonic cavities will be installed. The present RF acceleration system operates at 0.5 GHz and the additional 3rd harmonic and 3rd sub-harmonic cavities will operate at 1.5 GHz and 1.75 GHz, respectively. These cavities are essential to produce short 1.5 ps bunches with a design current of up to 0.8 mA per bunch. The total current in the storage ring is limited by the higher order mode damping capabilities of the SRF cavities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA032
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MOPHA033	Physical Parameter Identification of Cross-Coupled Gun and Buncher Cavity at REGAE	gun, resonance, cavity, coupling	857
	A.S. Nawaz, H. Werner TUHH, Hamburg, Germany M. Hoffmann, S. Pfeiffer, H. Schlarb DESY, Hamburg, Germany
	A reasonable description of the system dynamics is one of the key elements to achieve high performance control for accelerating modules. This paper depicts the system identification of a cross-coupled pair of cavities for the Relativistic Electron Gun for Atomic Exploration - REGAE. Two normal conducting copper cavities driven by a single RF source accelerate and compress a low charge electron bunch with sub 10 fs length at a repetition rate up to 50 Hz. It is shown how the model parameters of the cavities and the attached radio frequency subsystem are identified from data generated at the REGAE facility.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA033
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WEPJE008	Experimental Study of Wakefields in an X-band Photonic Band Gap Accelerating Structure	wakefield, HOM, coupling, electron	2689
	E.I. Simakov, S. Arsenyev, C.E. Buechler, R.L. Edwards, W.P. Romero LANL, Los Alamos, New Mexico, USA M.E. Conde, G. Ha, C.-J. Jing, J.G. Power, E.E. Wisniewski ANL, Argonne, Illinois, USA C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA
	Funding: This work is supported by U.S. Department of Energy (DOE) Office of Science Early Career Research Program. We designed an experiment to conduct a detailed investigation of higher order mode spectrum in a room-temperature traveling-wave photonic band gap (PBG) accelerating structure at 11.7 GHz. It has been long recognized that PBG structures have great potential in reducing long-range wakefields in accelerators. The first ever demonstration of acceleration in room-temperature PBG structures was conducted at MIT in 2005. Since then, the importance of that device has been recognized by many research institutions. However, the full experimental characterization of the wakefield spectrum in a beam test has not been performed to date. The Argonne Wakefield Accelerator (AWA) test facility at the Argonne National Laboratory represents a perfect site where this evaluation could be conducted with a single high charge electron bunch and with a train of bunches. Here we describe fabrication and tuning of PBG cells, the final cold-test of the traveling-wave accelerating structure, and the results of the beam testing at AWA.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE008
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WEPMA026	Higher Order Mode Propagation and Damping Studies on Axisymmetric Superconducting Multicell RF-Resonators	cavity, factory, damping, coupling	2812
	B.D. Isbarn, B. Riemann, M. Sommer, T. Weis DELTA, Dortmund, Germany
	Funding: Work supported by the BMBF under contract no. 05K13PEB Higher order mode (HOM) propagation and damping is a major concern in feasibility studies regarding the upcoming upgrade of BESSY II, named BESSY-VSR, which involves the utilization of superconducting multicell RF-resonators in a storage ring while maintaining a reasonably high beam current typical for third generation synchrotron radiation facilities. In addition to the computation of the typical figures of merit, we focus on studies of the mode propagation in axisymmetric structures. Due to the focus on axisymmetric studies we are able to use 2D codes to investigate in eigenmodes with substantial higher frequencies than usually considered with full 3D codes in parametric studies. In this work we present preliminary studies involving mode propagation in superconducting elliptical multicell cavities. G. Wüstefeld et al., Proc. of IPAC'11, San Sebastián, THPC014
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WEPMN026	Development of Non-resonant Perturbing Method for Tuning Traveling Wave Deflecting Structures	simulation, cavity, network, dipole	2985
	J.H. Tan, W. Fang, Q. Gu, Z.T. Zhao SINAP, Shanghai, People's Republic of China D.C. Tong TUB, Beijing, People's Republic of China
	For traveling wave accelerating structures, the tuning method assisted by bead pull technique based on non-resonant perturbation field distribution measurement has been widely used. Long periodic traveling wave deflecting structure, which operating at HEM11 mode, is difficult to use non-resonant perturbation method, and a improved method has been developed for measuring and tuning by "cage" type perturbing object at SINAP. The measurements on x-band traveling wave deflecting structure are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN026
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WEPTY018	Analysis of a Quasi-waveguide Multicell Resonator for SPX	cavity, wakefield, resonance, niobium	3299
	M.H. Awida, I.V. Gonin, T.N. Khabiboulline, A. Lunin, V.P. Yakovlev Fermilab, Batavia, Illinois, USA A. Zholents ANL, Argonne, Ilinois, USA
	A compact deflecting cavity is needed for the Short Pulse X-rays (SPX) at the Advanced Photon Source (APS) of Argonne national laboratory. The deflecting cavity has to quite efficient providing a 2 MV kick voltage and satisfying stringent requirements on aperture size and total cavity length. Meanwhile, the cavity should allow operation up to 100 mT peak surface magnetic field before quenching. In this paper, we report on the latest analysis carried out on the cavity structure to investigate frequency sensitivity to pressure fluctuations, frequency sensitivity to tuning forces, modal frequency, and wakefield losses.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY018
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WEPWI060	Cryogenic Test of Double Quarter Wave Crab Cavity for the LHC High Luminosity Upgrade	cavity, cryogenics, luminosity, radiation	3630
	B. P. Xiao, S.A. Belomestnykh, I. Ben-Zvi, C. Cullen, L.R. Hammons, C. Marques, J. Skaritka, S. Verdú-Andrés, Q. Wu BNL, Upton, Long Island, New York, USA L. Alberty, R. Calaga, O. Capatina CERN, Geneva, Switzerland S.A. Belomestnykh, I. Ben-Zvi Stony Brook University, Stony Brook, USA Z. Li SLAC, Menlo Park, California, USA
	Funding: Work partly supported by US LARP, by US DOE under contract No. DE-AC02-05CH11231 and through BSA under contract No. DE-AC02-98CH10886. Research supported by EU FP7 HiLumi LHC - Grant Agreement 284404. A Proof-of-Principle (PoP) Double Quarter Wave Crab Cavity (DQWCC) was designed and fabricated for the Large Hadron Collider (LHC) luminosity upgrade. A vertical cryogenic test has been done at Brookhaven National Lab (BNL). The cavity achieved 4.5 MV deflecting voltage with a quality factor above 3×10⁹. We report the test results of this design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI060
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THPF022	Design of the 325 MHz 4-Rod RFQ for the FAIR Proton Linac	rfq, dipole, simulation, operation	3733
	B. Koubek, H. Podlech, A. Schempp IAP, Frankfurt am Main, Germany
	Investigations on the 325 MHz 4-rod RFQ prototype for the FAIR proton linac have confirmed the feasibility of a 4-rod RFQ to work at frequencies above 300 MHz. This RFQ will accelerate protons from 95 keV to 3 MeV within a length of 3.3 m and will be powered by a 2.5 MW klystron. The mechanical and rf design of this RFQ are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF022
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Paper

Title

Other Keywords

Page

MOPWA032

Aspects of SRF Cavity Optimization for BESSY-VSR Upgrade

cavity, HOM, SRF, storage-ring

171

T. Galek, K. Brackebusch, T. Flisgen, J. Heller, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
B.D. Isbarn, B. Riemann, M. Sommer, T. Weis
DELTA, Dortmund, Germany

Funding: Work supported by Federal Ministry for Research and Education BMBF under contract 05K13HR1.
In this work we present a preliminary study of a long chain of cavities and some aspects involved in the optimization procedure. It is important to numerically model and optimize the SRF cavities with respect to external quality factors of the most dangerous higher order modes. BESSY-VSR is an upgrade scheme for the existing BESSY II storage ring aiming to simultaneously support variable electron pulse lengths. Currently, BESSY II supports long 15 ps bunches in the standard user optics configuration and short 1.5 ps bunches in a so-called low-α optics mode. In order to develop BESSY II into a variable electron pulse length storage ring, additional two sets of SRF higher-harmonic cavities will be installed. The present RF acceleration system operates at 0.5 GHz and the additional 3rd harmonic and 3rd sub-harmonic cavities will operate at 1.5 GHz and 1.75 GHz, respectively. These cavities are essential to produce short 1.5 ps bunches with a design current of up to 0.8 mA per bunch. The total current in the storage ring is limited by the higher order mode damping capabilities of the SRF cavities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA032

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MOPHA033

Physical Parameter Identification of Cross-Coupled Gun and Buncher Cavity at REGAE

gun, resonance, cavity, coupling

857

A.S. Nawaz, H. Werner
TUHH, Hamburg, Germany
M. Hoffmann, S. Pfeiffer, H. Schlarb
DESY, Hamburg, Germany

A reasonable description of the system dynamics is one of the key elements to achieve high performance control for accelerating modules. This paper depicts the system identification of a cross-coupled pair of cavities for the Relativistic Electron Gun for Atomic Exploration - REGAE. Two normal conducting copper cavities driven by a single RF source accelerate and compress a low charge electron bunch with sub 10 fs length at a repetition rate up to 50 Hz. It is shown how the model parameters of the cavities and the attached radio frequency subsystem are identified from data generated at the REGAE facility.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA033

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WEPJE008

Experimental Study of Wakefields in an X-band Photonic Band Gap Accelerating Structure

wakefield, HOM, coupling, electron

2689

E.I. Simakov, S. Arsenyev, C.E. Buechler, R.L. Edwards, W.P. Romero
LANL, Los Alamos, New Mexico, USA
M.E. Conde, G. Ha, C.-J. Jing, J.G. Power, E.E. Wisniewski
ANL, Argonne, Illinois, USA
C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA

Funding: This work is supported by U.S. Department of Energy (DOE) Office of Science Early Career Research Program.
We designed an experiment to conduct a detailed investigation of higher order mode spectrum in a room-temperature traveling-wave photonic band gap (PBG) accelerating structure at 11.7 GHz. It has been long recognized that PBG structures have great potential in reducing long-range wakefields in accelerators. The first ever demonstration of acceleration in room-temperature PBG structures was conducted at MIT in 2005. Since then, the importance of that device has been recognized by many research institutions. However, the full experimental characterization of the wakefield spectrum in a beam test has not been performed to date. The Argonne Wakefield Accelerator (AWA) test facility at the Argonne National Laboratory represents a perfect site where this evaluation could be conducted with a single high charge electron bunch and with a train of bunches. Here we describe fabrication and tuning of PBG cells, the final cold-test of the traveling-wave accelerating structure, and the results of the beam testing at AWA.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE008

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WEPMA026

Higher Order Mode Propagation and Damping Studies on Axisymmetric Superconducting Multicell RF-Resonators

cavity, factory, damping, coupling

2812

B.D. Isbarn, B. Riemann, M. Sommer, T. Weis
DELTA, Dortmund, Germany

Funding: Work supported by the BMBF under contract no. 05K13PEB
Higher order mode (HOM) propagation and damping is a major concern in feasibility studies regarding the upcoming upgrade of BESSY II, named BESSY-VSR*, which involves the utilization of superconducting multicell RF-resonators in a storage ring while maintaining a reasonably high beam current typical for third generation synchrotron radiation facilities. In addition to the computation of the typical figures of merit, we focus on studies of the mode propagation in axisymmetric structures. Due to the focus on axisymmetric studies we are able to use 2D codes to investigate in eigenmodes with substantial higher frequencies than usually considered with full 3D codes in parametric studies. In this work we present preliminary studies involving mode propagation in superconducting elliptical multicell cavities.
* G. Wüstefeld et al., Proc. of IPAC'11, San Sebastián, THPC014

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA026

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WEPMN026

Development of Non-resonant Perturbing Method for Tuning Traveling Wave Deflecting Structures

simulation, cavity, network, dipole

2985

J.H. Tan, W. Fang, Q. Gu, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
D.C. Tong
TUB, Beijing, People's Republic of China

For traveling wave accelerating structures, the tuning method assisted by bead pull technique based on non-resonant perturbation field distribution measurement has been widely used. Long periodic traveling wave deflecting structure, which operating at HEM11 mode, is difficult to use non-resonant perturbation method, and a improved method has been developed for measuring and tuning by "cage" type perturbing object at SINAP. The measurements on x-band traveling wave deflecting structure are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN026

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WEPTY018

Analysis of a Quasi-waveguide Multicell Resonator for SPX

cavity, wakefield, resonance, niobium

3299

M.H. Awida, I.V. Gonin, T.N. Khabiboulline, A. Lunin, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA
A. Zholents
ANL, Argonne, Ilinois, USA

A compact deflecting cavity is needed for the Short Pulse X-rays (SPX) at the Advanced Photon Source (APS) of Argonne national laboratory. The deflecting cavity has to quite efficient providing a 2 MV kick voltage and satisfying stringent requirements on aperture size and total cavity length. Meanwhile, the cavity should allow operation up to 100 mT peak surface magnetic field before quenching. In this paper, we report on the latest analysis carried out on the cavity structure to investigate frequency sensitivity to pressure fluctuations, frequency sensitivity to tuning forces, modal frequency, and wakefield losses.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY018

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WEPWI060

Cryogenic Test of Double Quarter Wave Crab Cavity for the LHC High Luminosity Upgrade

cavity, cryogenics, luminosity, radiation

3630

B. P. Xiao, S.A. Belomestnykh, I. Ben-Zvi, C. Cullen, L.R. Hammons, C. Marques, J. Skaritka, S. Verdú-Andrés, Q. Wu
BNL, Upton, Long Island, New York, USA
L. Alberty, R. Calaga, O. Capatina
CERN, Geneva, Switzerland
S.A. Belomestnykh, I. Ben-Zvi
Stony Brook University, Stony Brook, USA
Z. Li
SLAC, Menlo Park, California, USA

Funding: Work partly supported by US LARP, by US DOE under contract No. DE-AC02-05CH11231 and through BSA under contract No. DE-AC02-98CH10886. Research supported by EU FP7 HiLumi LHC - Grant Agreement 284404.
A Proof-of-Principle (PoP) Double Quarter Wave Crab Cavity (DQWCC) was designed and fabricated for the Large Hadron Collider (LHC) luminosity upgrade. A vertical cryogenic test has been done at Brookhaven National Lab (BNL). The cavity achieved 4.5 MV deflecting voltage with a quality factor above 3×10⁹. We report the test results of this design.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI060

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

THPF022

Design of the 325 MHz 4-Rod RFQ for the FAIR Proton Linac

rfq, dipole, simulation, operation

3733

B. Koubek, H. Podlech, A. Schempp
IAP, Frankfurt am Main, Germany

Investigations on the 325 MHz 4-rod RFQ prototype for the FAIR proton linac have confirmed the feasibility of a 4-rod RFQ to work at frequencies above 300 MHz. This RFQ will accelerate protons from 95 keV to 3 MeV within a length of 3.3 m and will be powered by a 2.5 MW klystron. The mechanical and rf design of this RFQ are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF022

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