SRF2015 - List of Keywords (higher-order-mode)

Paper	Title	Other Keywords	Page
THBA05	Higher Order Mode Absorbers for High Current SRF Applications	HOM, cavity, linac, operation	1036
	R.G. Eichhorn, J.V. Conway, T. Gruber, Y. He, G.H. Hoffstaetter, Y. Li, M. Liepe, T.I. O'Connell, P. Quigley, J. Sears, V.D. Shemelin, E.N. Smith, M. Tigner Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Efficient damping of the higher-order modes (HOMs) of the superconducting cavities is essential for any high current operation. The talk will provide an overview on the latest advances of HOM absorber development for high intensity SRF applications. As the ideal absorber does not exist, the different conceptual approaches will be presented and the associated issues are outlined. Design examples from various labs will be given that help explain the issues and resolutions. Some focus will be given to the Cornell HOM beamline absorber that was design for high current, short bunch operation with up to 400 W heating. The design will be reviewed and testing results will be reported.
	Slides THBA05 [4.022 MB]
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THPB071	Developments of SiC Damper for SuperKEKB Superconducting Cavity	HOM, cavity, operation, factory	1289
	M. Nishiwaki, K. Akai, T. Furuya, A. Kabe, S. Mitsunobu, Y. Morita KEK, Ibaraki, Japan
	Upgrade works for SuperKEKB is in the final stage and the commissioning operation will start in this JFY. Eight superconducting accelerating cavities were operated for more than ten years at KEKB electron ring and are to be used at SuperKEKB. The cavity operation at those high current accelerators requires sufficient absorption of the beam-induced HOM power. In KEKB, the absorbed HOM power of 16 kW in two ferrite dampers attached to each cavity was achieved at the beam current of 1.4 A. On the other hand, the expected HOM power at SuperKEKB is calculated to be 37 kW in the beam current of 2.6 A. To cope with the HOM power issue, we developed additional HOM dampers made of SiC to be installed to the downstream of the cavity module. From precise calculations, it was found that the additional dampers reduce the HOM power loads of the ferrite dampers more effectively than the large beam pipe model of cavity module, which is another option to reduce the HOM loads. New SiC dampers were fabricated and high power-tested. Those SiC dampers successfully absorbed the expected HOM power. In this report, we will describe the results of calculations and high-power RF tests of new SiC dampers.
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THPB089	HOM Coupler Performance in CW Regime in Horizontal and Vertical Tests	HOM, cavity, operation, coupling	1349
	N. Solyak, M.H. Awida, A. Grassellino, C.J. Grimm, A. Hocker, J.P. Holzbauer, T.N. Khabiboulline, O.S. Melnychuk, A.M. Rowe, D.A. Sergatskov, N. Solyak Fermilab, Batavia, Illinois, USA J.K. Sekutowicz DESY, Hamburg, Germany
	Power dissipation in HOM coupler antenna can limit cavity gradient in cw operation. XFEL design of HOM coupler, feedthrough and thermal connection to 2K pipe was accepted for LCLS-II cavity based on simulation results. Recently a series of vertical and horizontal tests was done to prove design for cw operation. In vertical test was found no effect of HOM coupler heating on high-Q cavity performance. In horizontal cryostat HOM coupler was tested up-to 23MV/m in continuous wave mode. Result proves that XFEL HOM coupler meets LCLS-II specifications.
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THPB104	Higher Order Modes Simulation and Measurements for 2400 MHz Cavity	HOM, cavity, damping, simulation	1394
	Ya.V. Shashkov, D.S. Bazyl, R.V. Donetskiy, M.V. Lalayan, N.P. Sobenin MEPhI, Moscow, Russia R. Calaga CERN, Geneva, Switzerland A.A. Zavadtsev Nano, Moscow, Russia M. Zobov INFN/LNF, Frascati (Roma), Italy
	Funding: Work supported by Ministry of Education and Science grant 3.245.2014/r and the EU FP7 HiLumi LHC – Grant Agreement 284404 In the frameworks of the High Luminosity LHC upgrade program an application of additional harmonic cavities operating at multiples of the main RF system frequency of 400 MHz is currently under discussion. The 800 MHz superconducting cavities with grooved beam pipes were suggested for implementation. A scaled aluminum prototype with a frequency of the operational mode of 2400 MHz was manufactured for testing the results of simulations. The load reflection coefficient measurements were performed as well as the Qload measurements for cavities with the load. Here we discuss the prototype design and report the obtained measurement results. Higher order modes, superconducting cavities, srf*
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Paper

Title

Other Keywords

Page

THBA05

Higher Order Mode Absorbers for High Current SRF Applications

HOM, cavity, linac, operation

1036

R.G. Eichhorn, J.V. Conway, T. Gruber, Y. He, G.H. Hoffstaetter, Y. Li, M. Liepe, T.I. O'Connell, P. Quigley, J. Sears, V.D. Shemelin, E.N. Smith, M. Tigner
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Efficient damping of the higher-order modes (HOMs) of the superconducting cavities is essential for any high current operation. The talk will provide an overview on the latest advances of HOM absorber development for high intensity SRF applications. As the ideal absorber does not exist, the different conceptual approaches will be presented and the associated issues are outlined. Design examples from various labs will be given that help explain the issues and resolutions. Some focus will be given to the Cornell HOM beamline absorber that was design for high current, short bunch operation with up to 400 W heating. The design will be reviewed and testing results will be reported.

Slides THBA05 [4.022 MB]

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THPB071

Developments of SiC Damper for SuperKEKB Superconducting Cavity

HOM, cavity, operation, factory

1289

M. Nishiwaki, K. Akai, T. Furuya, A. Kabe, S. Mitsunobu, Y. Morita
KEK, Ibaraki, Japan

Upgrade works for SuperKEKB is in the final stage and the commissioning operation will start in this JFY. Eight superconducting accelerating cavities were operated for more than ten years at KEKB electron ring and are to be used at SuperKEKB. The cavity operation at those high current accelerators requires sufficient absorption of the beam-induced HOM power. In KEKB, the absorbed HOM power of 16 kW in two ferrite dampers attached to each cavity was achieved at the beam current of 1.4 A. On the other hand, the expected HOM power at SuperKEKB is calculated to be 37 kW in the beam current of 2.6 A. To cope with the HOM power issue, we developed additional HOM dampers made of SiC to be installed to the downstream of the cavity module. From precise calculations, it was found that the additional dampers reduce the HOM power loads of the ferrite dampers more effectively than the large beam pipe model of cavity module, which is another option to reduce the HOM loads. New SiC dampers were fabricated and high power-tested. Those SiC dampers successfully absorbed the expected HOM power. In this report, we will describe the results of calculations and high-power RF tests of new SiC dampers.

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THPB089

HOM Coupler Performance in CW Regime in Horizontal and Vertical Tests

HOM, cavity, operation, coupling

1349

N. Solyak, M.H. Awida, A. Grassellino, C.J. Grimm, A. Hocker, J.P. Holzbauer, T.N. Khabiboulline, O.S. Melnychuk, A.M. Rowe, D.A. Sergatskov, N. Solyak
Fermilab, Batavia, Illinois, USA
J.K. Sekutowicz
DESY, Hamburg, Germany

Power dissipation in HOM coupler antenna can limit cavity gradient in cw operation. XFEL design of HOM coupler, feedthrough and thermal connection to 2K pipe was accepted for LCLS-II cavity based on simulation results. Recently a series of vertical and horizontal tests was done to prove design for cw operation. In vertical test was found no effect of HOM coupler heating on high-Q cavity performance. In horizontal cryostat HOM coupler was tested up-to 23MV/m in continuous wave mode. Result proves that XFEL HOM coupler meets LCLS-II specifications.

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reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text, ※ RIS/RefMan, ※ EndNote (xml)

THPB104

Higher Order Modes Simulation and Measurements for 2400 MHz Cavity

HOM, cavity, damping, simulation

1394

Ya.V. Shashkov, D.S. Bazyl, R.V. Donetskiy, M.V. Lalayan, N.P. Sobenin
MEPhI, Moscow, Russia
R. Calaga
CERN, Geneva, Switzerland
A.A. Zavadtsev
Nano, Moscow, Russia
M. Zobov
INFN/LNF, Frascati (Roma), Italy

Funding: *Work supported by Ministry of Education and Science grant 3.245.2014/r and the EU FP7 HiLumi LHC – Grant Agreement 284404
In the frameworks of the High Luminosity LHC upgrade program an application of additional harmonic cavities operating at multiples of the main RF system frequency of 400 MHz is currently under discussion. The 800 MHz superconducting cavities with grooved beam pipes were suggested for implementation. A scaled aluminum prototype with a frequency of the operational mode of 2400 MHz was manufactured for testing the results of simulations. The load reflection coefficient measurements were performed as well as the Qload measurements for cavities with the load. Here we discuss the prototype design and report the obtained measurement results.
Higher order modes, superconducting cavities, srf

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reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text, ※ RIS/RefMan, ※ EndNote (xml)