SRF2011 - List of Authors (Shemelin, V.D.)

Paper

Title

Page

Superconducting RF for the Cornell Energy-Recovery Linac Main Linac

90

M. Liepe, Y. He, G.H. Hoffstaetter, S. Posen, J. Sears, V.D. Shemelin, M. Tigner, N.R.A. Valles, V. Veshcherevich
CLASSE, Ithaca, New York, USA

Funding: Supported by NSF award DMR-0807731.
Cornell University is developing the superconducting RF technology required for the construction of a 100 mA hard X-ray light source driven by an Energy-Recovery Linac. Prototype components of the 5 GeV cw SRF main linac cryomodule are under development, fabrication and testing. This work includes an optimized 7-cell SRF cavity, a broadband HOM beamline absorber, and a 5 kW cw RF input coupler. In this paper we give an overview of these activities at Cornell.

MOPO057

Coupler Kick Studies in Cornell's 7-Cell Superconducting Cavities

232

N.R.A. Valles, M. Liepe, V.D. Shemelin
CLASSE, Ithaca, New York, USA

Cornell is developing a 5 GeV Energy Recovery Linac operating at 100 mA with very small emittances (~30 pm-rad at 77 pC bunch charge) in the horizontal and vertical directions. We investigate the effect of the fundamental RF power couplers of the main linac SRF cavities on the beam using the ACE3P software package. The cavities in the ERL main linac will be operated at very high loaded quality factors of up to 6.5·10⁷, corresponding to a full bandwidth of only 20 Hz. Cavity microphonics will detune the cavities by more than one bandwidth during operation, thereby causing a time dependent change of the coupler kick in addition to its fast oscillation at the RF frequency. In order to investigate the dependence of the coupler kick on the cavity frequency, we calculate the coupler kick given to the beam for the case of a detuned RF cavity. We show that a compensation stub geometry located opposite to the input coupler port can be optimized to reduce the overall kick given to the beam and the emittace growth caused by its time dependence.

TUPO044

Correction of a Superconducting Cavity Shape Due to Etching, Cooling Down and Tuning

482

V.D. Shemelin
CLASSE, Ithaca, New York, USA

Funding: Supported by NSF award DMR-0807731
Corrections of shape needed for an SRF cavity after fabrication are presented in a convenient form with a possibility to take into account different technological procedures, such as etching, cooling down and pre-loading.

Poster TUPO044 [0.599 MB]

TUPO013

Assembly of the International ERL Cryomodule at Daresbury Laboratory

382

P.A. McIntosh, R. Bate, P. Goudket, J.F. Orrett, S.M. Pattalwar
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
S.A. Belomestnykh, M. Liepe, H. Padamsee, P. Quigley, J. Sears, V.D. Shemelin, V. Veshcherevich
CLASSE, Ithaca, New York, USA
A. Büchner, F.G. Gabriel, P. Michel
HZDR, Dresden, Germany
M.A. Cordwell, T.J. Jones, J. Strachan
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
J.N. Corlett, D. Li, S.M. Lidia
LBNL, Berkeley, California, USA
T. Kimura, T.I. Smith
Stanford University, Stanford, California, USA
R.E. Laxdal
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
D. Proch, J.K. Sekutowicz
DESY, Hamburg, Germany

The collaborative development of an optimised cavity/cryomodule solution for application on ERL facilities is nearing completion. This paper outlines the progress of the module assembly and details the processes used for final cavity string integration. The preparation and installation of the high power couplers will be described, as will that of the HOM loads. The testing and integration of the various sub-components of the cryomodule are also detailed in this paper.

THPO012

Influence of Foreign Particles on the Quality Factor of a Superconducting Cavity

728

V.D. Shemelin, G.H. Hoffstaetter
CLASSE, Ithaca, New York, USA

Funding: Supported by NSF award DMR-0807731.
The quality factor of superconducting (SC) cavities of the Cornell Energy Recovery Linac (ERL) Injector measured in its horizontal cryostat appears systematically lower than in vertical tests. Furthermore, this lower value of the Q factor is scattered in a range of about Here, an explanation of these effects is presented taking into account contamination of the cavities by microscopic particles of ferrite used in the higher order mode (HOM) loads and other particles present in the vicinity of cavities during assembly of the horizontal cryostat. The average Q degradation and the scatter of Q values are used to estimate the size and the number of contaminants per cavity. We also analyze, which materials have relevant contaminants.

Paper	Title	Page
MOPO016	Superconducting RF for the Cornell Energy-Recovery Linac Main Linac	90
	M. Liepe, Y. He, G.H. Hoffstaetter, S. Posen, J. Sears, V.D. Shemelin, M. Tigner, N.R.A. Valles, V. Veshcherevich CLASSE, Ithaca, New York, USA
	Funding: Supported by NSF award DMR-0807731. Cornell University is developing the superconducting RF technology required for the construction of a 100 mA hard X-ray light source driven by an Energy-Recovery Linac. Prototype components of the 5 GeV cw SRF main linac cryomodule are under development, fabrication and testing. This work includes an optimized 7-cell SRF cavity, a broadband HOM beamline absorber, and a 5 kW cw RF input coupler. In this paper we give an overview of these activities at Cornell.

MOPO057	Coupler Kick Studies in Cornell's 7-Cell Superconducting Cavities	232
	N.R.A. Valles, M. Liepe, V.D. Shemelin CLASSE, Ithaca, New York, USA
	Cornell is developing a 5 GeV Energy Recovery Linac operating at 100 mA with very small emittances (~30 pm-rad at 77 pC bunch charge) in the horizontal and vertical directions. We investigate the effect of the fundamental RF power couplers of the main linac SRF cavities on the beam using the ACE3P software package. The cavities in the ERL main linac will be operated at very high loaded quality factors of up to 6.5·10⁷, corresponding to a full bandwidth of only 20 Hz. Cavity microphonics will detune the cavities by more than one bandwidth during operation, thereby causing a time dependent change of the coupler kick in addition to its fast oscillation at the RF frequency. In order to investigate the dependence of the coupler kick on the cavity frequency, we calculate the coupler kick given to the beam for the case of a detuned RF cavity. We show that a compensation stub geometry located opposite to the input coupler port can be optimized to reduce the overall kick given to the beam and the emittace growth caused by its time dependence.

TUPO044	Correction of a Superconducting Cavity Shape Due to Etching, Cooling Down and Tuning	482
	V.D. Shemelin CLASSE, Ithaca, New York, USA
	Funding: Supported by NSF award DMR-0807731 Corrections of shape needed for an SRF cavity after fabrication are presented in a convenient form with a possibility to take into account different technological procedures, such as etching, cooling down and pre-loading.
	Poster TUPO044 [0.599 MB]

TUPO013	Assembly of the International ERL Cryomodule at Daresbury Laboratory	382
	P.A. McIntosh, R. Bate, P. Goudket, J.F. Orrett, S.M. Pattalwar STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom S.A. Belomestnykh, M. Liepe, H. Padamsee, P. Quigley, J. Sears, V.D. Shemelin, V. Veshcherevich CLASSE, Ithaca, New York, USA A. Büchner, F.G. Gabriel, P. Michel HZDR, Dresden, Germany M.A. Cordwell, T.J. Jones, J. Strachan STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom J.N. Corlett, D. Li, S.M. Lidia LBNL, Berkeley, California, USA T. Kimura, T.I. Smith Stanford University, Stanford, California, USA R.E. Laxdal TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada D. Proch, J.K. Sekutowicz DESY, Hamburg, Germany
	The collaborative development of an optimised cavity/cryomodule solution for application on ERL facilities is nearing completion. This paper outlines the progress of the module assembly and details the processes used for final cavity string integration. The preparation and installation of the high power couplers will be described, as will that of the HOM loads. The testing and integration of the various sub-components of the cryomodule are also detailed in this paper.

THPO012	Influence of Foreign Particles on the Quality Factor of a Superconducting Cavity	728
	V.D. Shemelin, G.H. Hoffstaetter CLASSE, Ithaca, New York, USA
	Funding: Supported by NSF award DMR-0807731. The quality factor of superconducting (SC) cavities of the Cornell Energy Recovery Linac (ERL) Injector measured in its horizontal cryostat appears systematically lower than in vertical tests. Furthermore, this lower value of the Q factor is scattered in a range of about Here, an explanation of these effects is presented taking into account contamination of the cavities by microscopic particles of ferrite used in the higher order mode (HOM) loads and other particles present in the vicinity of cavities during assembly of the horizontal cryostat. The average Q degradation and the scatter of Q values are used to estimate the size and the number of contaminants per cavity. We also analyze, which materials have relevant contaminants.