LINAC2014 - List of Authors (Eichhorn, R.G.)

Paper

Title

Page

R&D Efforts for ERLs

394

R.G. Eichhorn
Cornell University, Ithaca, New York, USA

The last few years has seen extensive R&D for ERLs, with several prototype facilities now under construction or in operation. The Cornell ERL R&D program has reached major goals, with producing the world’s brightest beam from any photoinjector, reaching CW beam current of greaters than 75 mA, and reaching intrinsic quality factors of 10¹¹ in an SRF cavity installed in a cryomodule. The talk gives an overview of status of ERLs projects, and ERL R&D.

Slides TUIOA02 [8.803 MB]

MOPP018

Nitrogen-Doped 9-Cell Cavity Performance in the Cornell Horizontal Test Cryomodule

88

D. Gonnella, R.G. Eichhorn, F. Furuta, G.M. Ge, D.L. Hall, Y. He, G.H. Hoffstaetter, M. Liepe, T.I. O'Connel, S. Posen, P. Quigley, J. Sears, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
A. Grassellino, A. Romanenko
Fermilab, Batavia, Illinois, USA

Funding: U.S. Department of Energy
Cornell has recently completed construction and qualification of a horizontal cryomodule capable of holding a 9-cell ILC cavity. A nitrogen-doped niobium 9-cell cavity was assembled into the Horizontal Test Cryomodule (HTC) with a high Q input coupler and tested. We report on results from this test of a nitrogen-doped cavity in cryomodule and discuss the effects of cool down rate and thermal cycling on the residual resistance of the cavity.

MOPP020

Input Couplers for Cornell ERL

95

R.G. Eichhorn, P. Quigley, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
S.A. Belomestnykh
BNL, Upton, Long Island, New York, USA

Cornell has developed two types of input couplers for the Energy Recovery Linac (ERL) Project. Both couplers are 1.3 GHz CW coaxial couplers. The coupler for ERL injector is a 65 kW CW coupler with variable coupling (Qext = 9*E4 to 9*E5). The coupler for ERL main linac is a 5 kW CW coupler with fixed coupling. It can be easily modified for variable coupling operation. Couplers have been tested on test stands and in cryomodules and showed good performance.

TUPP016

Cornell ERL cavity production and vertical test results

F. Furuta, B. Bullock, B. Clasby, R.G. Eichhorn, B. Elmore, A. Ganshin, G.M. Ge, G.H. Hoffstaetter, J.J. Kaufman, M. Liepe, J. Sears
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

The Cornell ERL 7-cell cavities for the Main Linac Cryomodule (MLC), six 7-cells in total- have been fabricated, processed, and tested in the Cornell Laboratory for Accelerator-based Sciences and Education (CLASSE) vertical test pit. All have surpassed the specification values (Eacc=16.2MV/m with Qo of 2.0·10¹⁰ at 1.8K). In fact, the achieved Qo during vertical test were much higher than specs, the average of Qo is almost 3·10¹⁰ at 1.8K. In this poster, we will describe about our ERL cavity fabrication, preparation, and vertical testing results.

THPP017

Beam-Based HOM Studies of the Cornell Energy Recovery Linac 7-Cell SRF Cavity

869

D.L. Hall, A.C. Bartnik, M.G. Billing, R.G. Eichhorn, G.H. Hoffstaetter, M. Liepe, C.E. Mayes, P. Quigley, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: NSF Grant DMR-0807731
The 1.3 GHz 7-cell SRF cavity for the Cornell ERL main linac is optimized for high beam current ERL operation with injected CW beam currents of 100 mA. Beam stability at 100 mA requires very strong damping of the Higher-Order-Modes (HOM) in the cavity by HOM beamline absorbers at the ends of the cavity. To verify the optimized design of the cavity and the HOM damping scheme, a prototype 7-cell main linac cavity was installed into the Cornell Horizontal Test Cryomodule (HTC), and inserted into the beamline of the Cornell ERL high current photo-injector. A beam-based method was then used to search for the presence of dangerous HOMs. Individual HOMs were excited using a charge-modulated beam, after which their effect upon an unmodulated beam was observed using a BPM. Data collected was used to calculate loaded Q of observed HOMs. Results show that it is very unlikely that HOMs will cause BBU in the Cornell ERL. In addition, measurements of the temperature rise of the HOM absorber rings during high current CW beam tests were consistent with simulations, indicating that the optimized main linac cavity is capable of operating at the specified current of 100mA in an ERL configuration.

THPP019

Low Kick Coupler for Superconducting Cavities

876

R.G. Eichhorn, C. Egerer, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Results from the high current, low emittance photo injector at Cornell revealed that even with two opposing input couplers, the beam emittance is affected by the coupler kick. As a result, a coupler with low transverse kick is proposed for use in superconducting accelerating cavities. In this coupler, a rectangular waveguide transforms into a coaxial line inside the beam pipe. The geometry of the coupler is tuned to minimize the transverse kick that is important for linear accelerators with low emittance. The coupler can be used in ERL injectors or other linacs for high brightness light sources.

Paper	Title	Page
TUIOA02	R&D Efforts for ERLs	394
	R.G. Eichhorn Cornell University, Ithaca, New York, USA
	The last few years has seen extensive R&D for ERLs, with several prototype facilities now under construction or in operation. The Cornell ERL R&D program has reached major goals, with producing the world’s brightest beam from any photoinjector, reaching CW beam current of greaters than 75 mA, and reaching intrinsic quality factors of 10¹¹ in an SRF cavity installed in a cryomodule. The talk gives an overview of status of ERLs projects, and ERL R&D.
	Slides TUIOA02 [8.803 MB]

MOPP018	Nitrogen-Doped 9-Cell Cavity Performance in the Cornell Horizontal Test Cryomodule	88
	D. Gonnella, R.G. Eichhorn, F. Furuta, G.M. Ge, D.L. Hall, Y. He, G.H. Hoffstaetter, M. Liepe, T.I. O'Connel, S. Posen, P. Quigley, J. Sears, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA A. Grassellino, A. Romanenko Fermilab, Batavia, Illinois, USA
	Funding: U.S. Department of Energy Cornell has recently completed construction and qualification of a horizontal cryomodule capable of holding a 9-cell ILC cavity. A nitrogen-doped niobium 9-cell cavity was assembled into the Horizontal Test Cryomodule (HTC) with a high Q input coupler and tested. We report on results from this test of a nitrogen-doped cavity in cryomodule and discuss the effects of cool down rate and thermal cycling on the residual resistance of the cavity.

MOPP020	Input Couplers for Cornell ERL	95
	R.G. Eichhorn, P. Quigley, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA S.A. Belomestnykh BNL, Upton, Long Island, New York, USA
	Cornell has developed two types of input couplers for the Energy Recovery Linac (ERL) Project. Both couplers are 1.3 GHz CW coaxial couplers. The coupler for ERL injector is a 65 kW CW coupler with variable coupling (Qext = 9E4 to 9E5). The coupler for ERL main linac is a 5 kW CW coupler with fixed coupling. It can be easily modified for variable coupling operation. Couplers have been tested on test stands and in cryomodules and showed good performance.

TUPP016	Cornell ERL cavity production and vertical test results
	F. Furuta, B. Bullock, B. Clasby, R.G. Eichhorn, B. Elmore, A. Ganshin, G.M. Ge, G.H. Hoffstaetter, J.J. Kaufman, M. Liepe, J. Sears Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	The Cornell ERL 7-cell cavities for the Main Linac Cryomodule (MLC), six 7-cells in total- have been fabricated, processed, and tested in the Cornell Laboratory for Accelerator-based Sciences and Education (CLASSE) vertical test pit. All have surpassed the specification values (Eacc=16.2MV/m with Qo of 2.0·10¹⁰ at 1.8K). In fact, the achieved Qo during vertical test were much higher than specs, the average of Qo is almost 3·10¹⁰ at 1.8K. In this poster, we will describe about our ERL cavity fabrication, preparation, and vertical testing results.

THPP017	Beam-Based HOM Studies of the Cornell Energy Recovery Linac 7-Cell SRF Cavity	869
	D.L. Hall, A.C. Bartnik, M.G. Billing, R.G. Eichhorn, G.H. Hoffstaetter, M. Liepe, C.E. Mayes, P. Quigley, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: NSF Grant DMR-0807731 The 1.3 GHz 7-cell SRF cavity for the Cornell ERL main linac is optimized for high beam current ERL operation with injected CW beam currents of 100 mA. Beam stability at 100 mA requires very strong damping of the Higher-Order-Modes (HOM) in the cavity by HOM beamline absorbers at the ends of the cavity. To verify the optimized design of the cavity and the HOM damping scheme, a prototype 7-cell main linac cavity was installed into the Cornell Horizontal Test Cryomodule (HTC), and inserted into the beamline of the Cornell ERL high current photo-injector. A beam-based method was then used to search for the presence of dangerous HOMs. Individual HOMs were excited using a charge-modulated beam, after which their effect upon an unmodulated beam was observed using a BPM. Data collected was used to calculate loaded Q of observed HOMs. Results show that it is very unlikely that HOMs will cause BBU in the Cornell ERL. In addition, measurements of the temperature rise of the HOM absorber rings during high current CW beam tests were consistent with simulations, indicating that the optimized main linac cavity is capable of operating at the specified current of 100mA in an ERL configuration.

THPP019	Low Kick Coupler for Superconducting Cavities	876
	R.G. Eichhorn, C. Egerer, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Results from the high current, low emittance photo injector at Cornell revealed that even with two opposing input couplers, the beam emittance is affected by the coupler kick. As a result, a coupler with low transverse kick is proposed for use in superconducting accelerating cavities. In this coupler, a rectangular waveguide transforms into a coaxial line inside the beam pipe. The geometry of the coupler is tuned to minimize the transverse kick that is important for linear accelerators with low emittance. The coupler can be used in ERL injectors or other linacs for high brightness light sources.