LINAC2016 - List of Authors (Gonin, I.V.)

Paper	Title	Page
MOPLR007	Redesign of the End Group in the 3.9 GHz LCLS-II Cavity	145
	A. Lunin, I.V. Gonin, T.N. Khabiboulline, N. Solyak Fermilab, Batavia, Illinois, USA
	Funding: Operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the U.S. DOE Development and production of Linac Coherent Light Source II (LCLS-II) is underway. The central part of LCLS-II is a continuous wave superconducting RF (CW SCRF) electron linac. The 3.9 GHz third harmonic cavity similar to the XFEL design will be used in LCLS-II for linearizing the longitudinal beam profile. The initial design of the 3.9 GHz cavity developed for XFEL project has a large, 40 mm, beam pipe aperture for better higher-order mode (HOM) damping. It is resulted in dipole HOMs with frequencies nearby the operating mode, which causes difficulties with HOM coupler notch filter tuning. The CW linac operation requires an extra caution in the design of the HOM coupler in order to prevent its possible overheating. In this paper we present the modified 3.9 GHz cavity End Group for meeting the LCLS-II requirements LCLS-II 3.9 GHz Cryomodules, Physics Requirements Document, LCLSII-4.1-PR-0097-R1, SLAC, USA, 2015
	Poster MOPLR007 [1.590 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR007
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MOPLR015	Thermal-Mechanical Study of 3.9 GHz CW Coupler and Cavity for LCLS-II Project	171
	I.V. Gonin, E.R. Harms, T.N. Khabiboulline, N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Third harmonic system was originally developed by Fermilab for FLASH facility at DESY and then was adopted and modified by INFN for the XFEL project [1-3]. In contrast to XFEL project, all cryomodules in LCLS-II project will operate in CW regime with higher RF average power for 1.3 GHz and 3.9 GHz cavities and couplers. Design of the cavity and fundamental power coupler has been modified to satisfy LCLS-II requirements. In this paper we discuss the results of COMSOL thermal and mechanical analysis of the 3.9 GHz coupler and cavity to verify proposed modifica-tion of the design. For the dressed cavity we present simulations of Lorentz force detuning, helium pressure sensitivity df/dP and major mechanical resonances.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR015
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THPLR036	SRF Low-Beta Elliptical Resonator Two-Ring Stiffening	929
	E.N. Zaplatin FZJ, Jülich, Germany I.V. Gonin, T.N. Khabiboulline, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Elliptical SRF cavities are the basic accelerating structures for the high energy part of many accelerators. Since a series of external loads on the resonator walls predetermine the main working conditions of the SC cavities the detailed investigation of their mechanical properties should be conducted in parallel with the main RF design. The effects of very high electromagnetic fields that result in strong Lorentz forces and the pressure on cavity walls from the helium tank that also deforms the cavity shape, the tuning scheme resulting in the change of accelerating field profile and mechanical eigen resonances of cavities which are the main source of the microphonics must be taken into account during integrated design of the resonator and its liquid helium vessel. SRF elliptical cavities for the medium energies (β=v/c is around 0.6) inherently have more flexible shape and their ultimate stiffening with a "standard" stiffening rings installed between resonator cells becomes problematic. The second row of the rings should enhance the overall cavity rigidity. In the paper we report the basic investigations of the cavity two-row ring stiffening using FNAL 650 MHz β=0.61 as an example. The single-cell investigation results were used as the reference to develop the ultimate scheme of the helium vessel structure to ensure the best resonator stability.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR036
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THPLR041	650 MHz Elliptical Superconducting RF Cavities for PIP-II Project	943
	I.V. Gonin, E. Borissov, A. Grassellino, C.J. Grimm, V. Jain, S. Kazakov, V.A. Lebedev, A. Lunin, C.S. Mishra, D.V. Mitchell, T.H. Nicol, Y.M. Pischalnikov, G.V. Romanov, A.M. Rowe, N.K. Sharma, N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	The PIP-II 800 MeV linac employs 650 MHz elliptical 5-cell CW-capable cavities to accelerate up to 2 mA peak beam current of H⁻ in the energy range 185 - 800 MeV. The low beta (LB) βG = 0.61 portion should accelerate from 185 MeV-500 MeV using 33 LB dressed cavities in 11 cryomodules. The high beta (HB) βG = 0.92 portion of the linac should accelerate from 500 to 800 MeV using 24 HB dressed cavities in 4 cryomodules. The development of both LB and HB cavities is going on under IIFC collaboration. The development of LB cavity initiated at VECC Kolkatta and HB cavity is going at RRCAT, Indore. This paper present design methodology adopted starting from RF design to get mechanical dimensions of the RF cells and then explains dressing of the cavity for both low beta and high beta cavities. Further the tuner design and its integration to the dressed cavity is discussed. Paper also explains the salient design features of these dressed cavities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR041
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Paper

Title

Page

Redesign of the End Group in the 3.9 GHz LCLS-II Cavity

145

A. Lunin, I.V. Gonin, T.N. Khabiboulline, N. Solyak
Fermilab, Batavia, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the U.S. DOE
Development and production of Linac Coherent Light Source II (LCLS-II) is underway. The central part of LCLS-II is a continuous wave superconducting RF (CW SCRF) electron linac. The 3.9 GHz third harmonic cavity similar to the XFEL design will be used in LCLS-II for linearizing the longitudinal beam profile*. The initial design of the 3.9 GHz cavity developed for XFEL project has a large, 40 mm, beam pipe aperture for better higher-order mode (HOM) damping. It is resulted in dipole HOMs with frequencies nearby the operating mode, which causes difficulties with HOM coupler notch filter tuning. The CW linac operation requires an extra caution in the design of the HOM coupler in order to prevent its possible overheating. In this paper we present the modified 3.9 GHz cavity End Group for meeting the LCLS-II requirements
* LCLS-II 3.9 GHz Cryomodules, Physics Requirements Document, LCLSII-4.1-PR-0097-R1, SLAC, USA, 2015

Poster MOPLR007 [1.590 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR007

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

MOPLR015

Thermal-Mechanical Study of 3.9 GHz CW Coupler and Cavity for LCLS-II Project

171

I.V. Gonin, E.R. Harms, T.N. Khabiboulline, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Third harmonic system was originally developed by Fermilab for FLASH facility at DESY and then was adopted and modified by INFN for the XFEL project [1-3]. In contrast to XFEL project, all cryomodules in LCLS-II project will operate in CW regime with higher RF average power for 1.3 GHz and 3.9 GHz cavities and couplers. Design of the cavity and fundamental power coupler has been modified to satisfy LCLS-II requirements. In this paper we discuss the results of COMSOL thermal and mechanical analysis of the 3.9 GHz coupler and cavity to verify proposed modifica-tion of the design. For the dressed cavity we present simulations of Lorentz force detuning, helium pressure sensitivity df/dP and major mechanical resonances.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR015

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

THPLR036

SRF Low-Beta Elliptical Resonator Two-Ring Stiffening

929

E.N. Zaplatin
FZJ, Jülich, Germany
I.V. Gonin, T.N. Khabiboulline, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Elliptical SRF cavities are the basic accelerating structures for the high energy part of many accelerators. Since a series of external loads on the resonator walls predetermine the main working conditions of the SC cavities the detailed investigation of their mechanical properties should be conducted in parallel with the main RF design. The effects of very high electromagnetic fields that result in strong Lorentz forces and the pressure on cavity walls from the helium tank that also deforms the cavity shape, the tuning scheme resulting in the change of accelerating field profile and mechanical eigen resonances of cavities which are the main source of the microphonics must be taken into account during integrated design of the resonator and its liquid helium vessel. SRF elliptical cavities for the medium energies (β=v/c is around 0.6) inherently have more flexible shape and their ultimate stiffening with a "standard" stiffening rings installed between resonator cells becomes problematic. The second row of the rings should enhance the overall cavity rigidity. In the paper we report the basic investigations of the cavity two-row ring stiffening using FNAL 650 MHz β=0.61 as an example. The single-cell investigation results were used as the reference to develop the ultimate scheme of the helium vessel structure to ensure the best resonator stability.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR036

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THPLR041

650 MHz Elliptical Superconducting RF Cavities for PIP-II Project

943

I.V. Gonin, E. Borissov, A. Grassellino, C.J. Grimm, V. Jain, S. Kazakov, V.A. Lebedev, A. Lunin, C.S. Mishra, D.V. Mitchell, T.H. Nicol, Y.M. Pischalnikov, G.V. Romanov, A.M. Rowe, N.K. Sharma, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

The PIP-II 800 MeV linac employs 650 MHz elliptical 5-cell CW-capable cavities to accelerate up to 2 mA peak beam current of H⁻ in the energy range 185 - 800 MeV. The low beta (LB) βG = 0.61 portion should accelerate from 185 MeV-500 MeV using 33 LB dressed cavities in 11 cryomodules. The high beta (HB) βG = 0.92 portion of the linac should accelerate from 500 to 800 MeV using 24 HB dressed cavities in 4 cryomodules. The development of both LB and HB cavities is going on under IIFC collaboration. The development of LB cavity initiated at VECC Kolkatta and HB cavity is going at RRCAT, Indore. This paper present design methodology adopted starting from RF design to get mechanical dimensions of the RF cells and then explains dressing of the cavity for both low beta and high beta cavities. Further the tuner design and its integration to the dressed cavity is discussed. Paper also explains the salient design features of these dressed cavities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR041

Export •

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