IPAC2014 - List of Keywords (higher-order-mode)

Paper	Title	Other Keywords	Page
WEPRI013	Investigation of Cryomodules for the Mainz Energy-recovering Superconducting Accelerator MESA	cryomodule, linac, HOM, operation	2505
	F. Schlander, K. Aulenbacher, R.G. Heine, D. Simon IKP, Mainz, Germany A. Arnold HZDR, Dresden, Germany
	Funding: Work supported by the German Federal Ministery of Education and Research (BMBF) and German Research Foundation (DFG) under the Cluster of Excellence "PRISMA" For the multiturn accelerator MESA it is planned to employ superconducting technology for the main linac, which is supposed to provide an energy gain of 50 MeV per turn. As continuous wave operation is mandatory for the experiments, it is important to minimise the cryogenic losses, hence to find cavities and the corresponding cryomodule meeting the framework conditions for the accelerator. The findings and the current statuts will be reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI013
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WEPRI076	Higher Order Mode Damping in Superconducting Spoke Cavities	HOM, cavity, damping, superconductivity	2669
	C.S. Hopper, J.R. Delayen ODU, Norfolk, Virginia, USA
	Parasitic higher order modes (HOMs) can be severely detrimental to the performance of superconducting cavities. For this reason, the mode spectrum and beam coupling strength must be examined in detail to determine which modes must be damped. One advantage of the spoke cavity geometry is that couplers can be placed on the outer body of the cavity rather than in the beam line space. We present an overview of the HOM properties of spoke cavities and methods for suppressing the most harmful ones.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI076
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THPRI065	Effects of Beam Loading and Higher-order Modes in RF Cavities for Muon Ionization Cooling	cavity, beam-loading, plasma, space-charge	3921
	M. Chung, A.V. Tollestrup, K. Yonehara Fermilab, Batavia, Illinois, USA B.T. Freemire IIT, Chicago, Illinois, USA F. Marhauser Muons, Inc, Illinois, USA
	Envisioned muon ionization cooling channel is based on vaccum and/or gas-filled RF cavities of frequencies of 325 and 650 MHz. In particular, to meet the luminosity requirement for a muon collider, the muon beam intensity should be on the order of 10¹² muons per bunch. In this high beam intensity, transient beam loading can significantly reduce the accelerating gradients and deteriorate the beam quality. We estimate this beam loading effect using an equivalent circuit model. For gas-filled cavity case, the beam loading is compared with plasma loading. We also investigate the excitation of higher-order modes and their effects on the performance of the cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI065
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THPRI112	Basic Research on RF Absorbing Ceramics for Beam Line HOM Absorbers	HOM, damping, vacuum, linac	4040
	R.G. Eichhorn, P. Quigley, V.D. Shemelin Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA M. Carty Alfred University, Alfred, New York, USA J. Matteson, A. Rae NanoMaterials Innovation Center LLC, Painted Post, USA
	Higher Order Mode (HOM) absorbers for future high current machines have been a challenging component for many years. Even though many different materials are commercially, none of them seems to fully qualify for accelerator applications. Some of them are brittle or chippy, others porous, have small bandwidth of absorption, a high dc resistivity leading to charge-up or are unreliable in terms of batch to batch variations. Alfred University and Cornell University have recently partnered in developing a dedicated absorber ceramic material that tries to overcome these limitations. We will report on results from small samples of different compositions we produced based on SiC, graphene and graphite.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI112
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

WEPRI013

Investigation of Cryomodules for the Mainz Energy-recovering Superconducting Accelerator MESA

cryomodule, linac, HOM, operation

2505

F. Schlander, K. Aulenbacher, R.G. Heine, D. Simon
IKP, Mainz, Germany
A. Arnold
HZDR, Dresden, Germany

Funding: Work supported by the German Federal Ministery of Education and Research (BMBF) and German Research Foundation (DFG) under the Cluster of Excellence "PRISMA"
For the multiturn accelerator MESA it is planned to employ superconducting technology for the main linac, which is supposed to provide an energy gain of 50 MeV per turn. As continuous wave operation is mandatory for the experiments, it is important to minimise the cryogenic losses, hence to find cavities and the corresponding cryomodule meeting the framework conditions for the accelerator. The findings and the current statuts will be reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI013

Export •

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

WEPRI076

Higher Order Mode Damping in Superconducting Spoke Cavities

HOM, cavity, damping, superconductivity

2669

C.S. Hopper, J.R. Delayen
ODU, Norfolk, Virginia, USA

Parasitic higher order modes (HOMs) can be severely detrimental to the performance of superconducting cavities. For this reason, the mode spectrum and beam coupling strength must be examined in detail to determine which modes must be damped. One advantage of the spoke cavity geometry is that couplers can be placed on the outer body of the cavity rather than in the beam line space. We present an overview of the HOM properties of spoke cavities and methods for suppressing the most harmful ones.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI076

Export •

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

THPRI065

Effects of Beam Loading and Higher-order Modes in RF Cavities for Muon Ionization Cooling

cavity, beam-loading, plasma, space-charge

3921

M. Chung, A.V. Tollestrup, K. Yonehara
Fermilab, Batavia, Illinois, USA
B.T. Freemire
IIT, Chicago, Illinois, USA
F. Marhauser
Muons, Inc, Illinois, USA

Envisioned muon ionization cooling channel is based on vaccum and/or gas-filled RF cavities of frequencies of 325 and 650 MHz. In particular, to meet the luminosity requirement for a muon collider, the muon beam intensity should be on the order of 10¹² muons per bunch. In this high beam intensity, transient beam loading can significantly reduce the accelerating gradients and deteriorate the beam quality. We estimate this beam loading effect using an equivalent circuit model. For gas-filled cavity case, the beam loading is compared with plasma loading. We also investigate the excitation of higher-order modes and their effects on the performance of the cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI065

Export •

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

THPRI112

Basic Research on RF Absorbing Ceramics for Beam Line HOM Absorbers

HOM, damping, vacuum, linac

4040

R.G. Eichhorn, P. Quigley, V.D. Shemelin
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
M. Carty
Alfred University, Alfred, New York, USA
J. Matteson, A. Rae
NanoMaterials Innovation Center LLC, Painted Post, USA

Higher Order Mode (HOM) absorbers for future high current machines have been a challenging component for many years. Even though many different materials are commercially, none of them seems to fully qualify for accelerator applications. Some of them are brittle or chippy, others porous, have small bandwidth of absorption, a high dc resistivity leading to charge-up or are unreliable in terms of batch to batch variations. Alfred University and Cornell University have recently partnered in developing a dedicated absorber ceramic material that tries to overcome these limitations. We will report on results from small samples of different compositions we produced based on SiC, graphene and graphite.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI112

Export •

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