LINAC2014 - List of Authors (Lunin, A.)

Paper

Title

Page

Development of 5-Cell β=0.9 650 MHz Elliptical Cavities for Project X

171

I.V. Gonin, M.H. Awida, M.H. Foley, A. Grassellino, C.J. Grimm, T.N. Khabiboulline, A. Lunin, A.M. Rowe, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Several 5-cell 650 MHz elliptical cavities have been fabricated for the PIP-II Project. Two versions of the cavities have been designed to accelerate protons of relative group velocity of β=0.9 and β=0.92 in the high energy region of the linac. In this paper, we report the development status of these cavities, summarize the results of the quality control measurements performed on five initial prototypes, and outline the VTS test results.

MOPP053

TTF-III Coupler Modification for CW Operation

174

I.V. Gonin, T.N. Khabiboulline, A. Lunin, O.V. Prokofiev, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

LCLS-II linac is based on XFEL/ILC superconducting technology, but CW regime of operation requires the modification of components to satisfy LCLS-II requirements. TTF-III coupler is considered as a candidate for a fundamental power coupler for the 1.3 GHz 9-cell accelerating structure at the LCLS-II project. In this paper we discuss the results of multiphysics analysis of the coupler working at various operating regimes. Two major modifications are proposed in order to meet the LCLS-II requirements and eliminate possible overheating: reducing the length of antenna (cold part) and increasing the thickness of a cooper plating on the inner conductor of the warm part of the coupler.

MOPP054

Continuous-Wave Horizontal Tests of Dressed 1.3 GHz SRF Cavities for LCLS-II

177

A. Hocker, A.C. Crawford, M. Geynisman, J.P. Holzbauer, A. Lunin, D.A. Sergatskov, N. Solyak, A.I. Sukhanov
Fermilab, Batavia, Illinois, USA

Funding: United States Department of Energy, Contract No. DE-AC02-07CH11359
Fermilab’s Horizontal Test Stand has recently been upgraded to provide CW RF testing capabilities in support of the LCLS-II project at SLAC. Several cavities have been tested in this new configuration in order to validate component designs and processes for meeting the requirements of LCLS-II. Areas of study included gradient and Q0 performance and their dependence on extrinsic factors, thermal performance of the input coupler and HOM feedthroughs, and microphonics and RF control. A description of the testing and the results obtained are presented.

Poster MOPP054 [0.276 MB]

THPP051

Design of a Quasi-Waveguide Multicell Deflecting Cavity for the Advanced Photon Source

966

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

This paper reports the electromagnetic design of a 2815 MHz Quasi-waveguide Multicell Resonator (called QMiR) being considered as a transverse RF deflecting cavity for the Advanced Photon Source’s (APS) Short Pulse X-ray project. QMiR forms a trapped dipole mode inside a beam vacuum chamber while High Order Modes (HOM) are heavily loaded. It results a sparse HOM spectrum, makes HOM couplers unnecessary and allows to simplify the cavity mechanical design. The form of electrodes is optimized for producing 2 MV of deflecting voltage and keeping low peak surface electric and magnetic fields of 54 MV/m and 75 mT respectively. Results of detailed EM analysis, including HOM damping at the actual geometry of beam vacuum chamber, will be presented.

Poster THPP051 [1.250 MB]

THPP054

Study of Coupler's Effect in Third Harmonic Section of LCLS-II SC Linac

969

A. Saini, A. Lunin, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA
T.O. Raubenheimer
SLAC, Menlo Park, California, USA

The Linac Coherent Light Source (LCLS) is an x-ray free electron laser facility. The proposed upgrade of the LCLS facility is based on construction of 4 GeV superconducting (SC) linac which will use two stage bunch compression scheme in order to achieve short bunches with high peak current. In order to reduce non-linear effects in first bunch compressor, third harmonic section is utilized to linearize longitudinal phase space of the beam. However, transverse phase space of beam may get distorted due to coupler RF kicks and coupler wake kicks resulting from the asymmetry of input and HOM couplers in 3.9 GHz cavity. In this paper, we discuss coupler's effects and estimate resulting emittance dilution in third harmonic section. Local compensation of coupler kicks using different orientation of cavities are also addressed.

THPP060

Effect of Cavity Couplers Field on the Beam Dynamics of the LCLS-II Injector

989

A. Vivoli, A. Lunin, A. Saini, N. Solyak
Fermilab, Batavia, Illinois, USA
A.C. Bartnik, I.V. Bazarov, B.M. Dunham, C.M. Gulliford, C.E. Mayes
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
D. Dowell, Z. Li, T.O. Raubenheimer, J.F. Schmerge, T. Vecchione, F. Zhou
SLAC, Menlo Park, California, USA
D. Filippetto, R. Huang, C. F. Papadopoulos, H.J. Qian, S.P. Virostek, R.P. Wells
LBNL, Berkeley, California, USA

LCLS-II is a new light source based on a continuous wave (cw) superconducting linac to be built at SLAC. The Injector section of the linac creates the elecron beam and accelerates it up to about 100 MeV. The couplers of the accelerating cavities produce an asymmetric field resulting in a beam offset and, most importantly, in a significant transverse emittance dilution, if not compensated. In this paper we describe the simulations of the LCLS-II injector taking into account the cavity couplers effect and some mitigation techniques to reduce its impact on the beam quality.

Paper	Title	Page
MOPP052	Development of 5-Cell β=0.9 650 MHz Elliptical Cavities for Project X	171
	I.V. Gonin, M.H. Awida, M.H. Foley, A. Grassellino, C.J. Grimm, T.N. Khabiboulline, A. Lunin, A.M. Rowe, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Several 5-cell 650 MHz elliptical cavities have been fabricated for the PIP-II Project. Two versions of the cavities have been designed to accelerate protons of relative group velocity of β=0.9 and β=0.92 in the high energy region of the linac. In this paper, we report the development status of these cavities, summarize the results of the quality control measurements performed on five initial prototypes, and outline the VTS test results.

MOPP053	TTF-III Coupler Modification for CW Operation	174
	I.V. Gonin, T.N. Khabiboulline, A. Lunin, O.V. Prokofiev, N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	LCLS-II linac is based on XFEL/ILC superconducting technology, but CW regime of operation requires the modification of components to satisfy LCLS-II requirements. TTF-III coupler is considered as a candidate for a fundamental power coupler for the 1.3 GHz 9-cell accelerating structure at the LCLS-II project. In this paper we discuss the results of multiphysics analysis of the coupler working at various operating regimes. Two major modifications are proposed in order to meet the LCLS-II requirements and eliminate possible overheating: reducing the length of antenna (cold part) and increasing the thickness of a cooper plating on the inner conductor of the warm part of the coupler.

MOPP054	Continuous-Wave Horizontal Tests of Dressed 1.3 GHz SRF Cavities for LCLS-II	177
	A. Hocker, A.C. Crawford, M. Geynisman, J.P. Holzbauer, A. Lunin, D.A. Sergatskov, N. Solyak, A.I. Sukhanov Fermilab, Batavia, Illinois, USA
	Funding: United States Department of Energy, Contract No. DE-AC02-07CH11359 Fermilab’s Horizontal Test Stand has recently been upgraded to provide CW RF testing capabilities in support of the LCLS-II project at SLAC. Several cavities have been tested in this new configuration in order to validate component designs and processes for meeting the requirements of LCLS-II. Areas of study included gradient and Q0 performance and their dependence on extrinsic factors, thermal performance of the input coupler and HOM feedthroughs, and microphonics and RF control. A description of the testing and the results obtained are presented.
	Poster MOPP054 [0.276 MB]

THPP051	Design of a Quasi-Waveguide Multicell Deflecting Cavity for the Advanced Photon Source	966
	A. Lunin, I.V. Gonin, T.N. Khabiboulline, V.P. Yakovlev Fermilab, Batavia, Illinois, USA A. Zholents ANL, Argonne, Ilinois, USA
	This paper reports the electromagnetic design of a 2815 MHz Quasi-waveguide Multicell Resonator (called QMiR) being considered as a transverse RF deflecting cavity for the Advanced Photon Source’s (APS) Short Pulse X-ray project. QMiR forms a trapped dipole mode inside a beam vacuum chamber while High Order Modes (HOM) are heavily loaded. It results a sparse HOM spectrum, makes HOM couplers unnecessary and allows to simplify the cavity mechanical design. The form of electrodes is optimized for producing 2 MV of deflecting voltage and keeping low peak surface electric and magnetic fields of 54 MV/m and 75 mT respectively. Results of detailed EM analysis, including HOM damping at the actual geometry of beam vacuum chamber, will be presented.
	Poster THPP051 [1.250 MB]

THPP054	Study of Coupler's Effect in Third Harmonic Section of LCLS-II SC Linac	969
	A. Saini, A. Lunin, N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA T.O. Raubenheimer SLAC, Menlo Park, California, USA
	The Linac Coherent Light Source (LCLS) is an x-ray free electron laser facility. The proposed upgrade of the LCLS facility is based on construction of 4 GeV superconducting (SC) linac which will use two stage bunch compression scheme in order to achieve short bunches with high peak current. In order to reduce non-linear effects in first bunch compressor, third harmonic section is utilized to linearize longitudinal phase space of the beam. However, transverse phase space of beam may get distorted due to coupler RF kicks and coupler wake kicks resulting from the asymmetry of input and HOM couplers in 3.9 GHz cavity. In this paper, we discuss coupler's effects and estimate resulting emittance dilution in third harmonic section. Local compensation of coupler kicks using different orientation of cavities are also addressed.

THPP060	Effect of Cavity Couplers Field on the Beam Dynamics of the LCLS-II Injector	989
	A. Vivoli, A. Lunin, A. Saini, N. Solyak Fermilab, Batavia, Illinois, USA A.C. Bartnik, I.V. Bazarov, B.M. Dunham, C.M. Gulliford, C.E. Mayes Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA D. Dowell, Z. Li, T.O. Raubenheimer, J.F. Schmerge, T. Vecchione, F. Zhou SLAC, Menlo Park, California, USA D. Filippetto, R. Huang, C. F. Papadopoulos, H.J. Qian, S.P. Virostek, R.P. Wells LBNL, Berkeley, California, USA
	LCLS-II is a new light source based on a continuous wave (cw) superconducting linac to be built at SLAC. The Injector section of the linac creates the elecron beam and accelerates it up to about 100 MeV. The couplers of the accelerating cavities produce an asymmetric field resulting in a beam offset and, most importantly, in a significant transverse emittance dilution, if not compensated. In this paper we describe the simulations of the LCLS-II injector taking into account the cavity couplers effect and some mitigation techniques to reduce its impact on the beam quality.