IPAC2016 - List of Authors (Eichhorn, R.G.)

Paper	Title	Page
WEPMR018	Time Resolved Cryogenic Cooling Analysis of the Cornell Injector Cryomodule	2298
	R.G. Eichhorn, A.C. Bartnik, B.M. Dunham, G.M. Ge, G.H. Hoffstaetter, H. Lee, M. Liepe, S.R. Markham, T.I. O'Connell, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	To demonstrate key parameters of a an energy recovery linac (ERL) at Cornel, an injector based on a photo gun and an SRF cryomodule was designed and built. The goal was to demonstrate high current generation while achieving low emittances. While the emittance goal has been reached, the current achieved so far is 75 mA. Even though this is a world record, it is still below the targeted 100 mA. While ramping up the current we observed excessive heating in the fundamental power coupler which we were able to track down to insufficient cooling of the 80 K intercepts. These intercepts are cooled by a stream of parallel cryogenic flows which we found to be unbalanced. In this paper we will review the finding, describe the analysis we did, modeling of the parallel flow and the modifications made to the module to overcome the heating.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR018
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WEPMR020	First Cool-down of the Cornell ERL Main Linac Cryo-Module	2305
	R.G. Eichhorn, J.V. Conway, F. Furuta, G.M. Ge, D. Gonnella, T. Gruber, G.H. Hoffstaetter, J.J. Kaufman, M. Liepe, T.I. O'Connell, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Cornell University has finished building a 10 m long superconducting accelerator module as a prototype of the main linac of a proposed ERL facility. This module houses 6 superconducting cavities- operated at 1.8 K in continuous wave (CW) mode with a design field of 16 MV/m and a Quality factor of 2x10¹⁰. We wil shortly review the design and focus on reporting on the first cool-down of this module. We will giving data for various cool-down scenarios (fast/ slow), uniformity and performance
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR020
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WEPMR021	HOM Measurements for Cornell's High-current CW ERL Cryomodule	2309
	F. Furuta, R.G. Eichhorn, G.M. Ge, D. Gonnella, G.H. Hoffstaetter, M. Liepe, P. Quigley, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	The main linac cryomodule (MLC) for the future energy-recovery linac (ERL) based synchrotron-light facility at Cornell had been designed, fabricated, and tested. It houses 6 SRF cavities with individual higher order-modes (HOMs)absorbers and one magnet/ BPM section. We will report the HOM study on MLC.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR021
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WEPMR022	ERL Main Linac Cryomodule Cavity Performance and Effect of Thermal Cycling	2312
	F. Furuta, J. Dobbins, R.G. Eichhorn, G.M. Ge, D. Gonnella, G.H. Hoffstaetter, M. Liepe, T.I. O'Connell, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Cornell has designed, fabricated, and tested a high current (100 mA) CW SRF prototype cryomodule for the future energy-recovery linac (ERL) based synchrotron-light facility at Cornell . It houses six 7-cell SRF cavities with individual HOM absorbers and one magnet/ BPM section. Cavities are targeted to operate with high Qo of 2.0·10¹⁰ at 16.2 MV/m, 1.8 K in continuous wave (CW) mode. We will report the RF test results of 7-cell cavities in this cryomodule after initial cooldown and several thermal cycles with different cooldown method.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR022
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WEPMR025	Improved N-Doping Protocols for SRF Cavities	2323
	D. Gonnella, R.G. Eichhorn, F. Furuta, G.M. Ge, T. Gruber, G.H. Hoffstaetter, J.J. Kaufman, P.N. Koufalis, M. Liepe, J.T. Maniscalco Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: NSF, DOE Nitrogen-doping has been shown to consistently produce better quality factors in SRF cavities than is achievable with standard preparation techniques. Unfortunately, nitrogen-doping typically brings with it lower quench fields and higher sensitivities of residual resistance to trapped magnetic flux. Here we present work to understand these effects in hopes of mitigating them while maintaining the high Q desired by future projects. Using a nitrogen diffusion simulation, material parameters of nitrogen-doped cavities can be predicted prior to doping. These simulations results are consistent with SIMS data taken from samples treated with cavities. The nature of doping's effect on quench field has also been studied using CW and pulsed measurements. These results have allowed us to better understand the nature of nitrogen-doping and its effect on cavity performance.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR025
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THPMB004	Improving Energy Spread and Stability of a Recirculating Few-turn Linac	3222
	F. Hug IKP, Mainz, Germany M. Arnold, T. Kürzeder, N. Pietralla TU Darmstadt, Darmstadt, Germany R.G. Eichhorn Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Supported by the DFG through CRC 634, RTG 2128 and PRISMA cluster of excellence A non-isochronous recirculation scheme which helps cancelling out errors coming from the RF-jitters in a recirculating linac will be presented. Non-isochronous recirculation is the common operation mode for synchrotrons or microtrons. In such a scheme the recirculation arcs provide a non-zero longitudinal dispersion, while the particle bunches are accelerated at a certain phase off-crest with respect to the maximum of the accelerating field. In few-turn linacs and microtrons such beam dynamics can be used to reduce the energy spread. To do so the longitudinal phase advance needs to be set to a half-integer number of oscillations in phase space. Then errors from linac RF-systems cancel out and the energy spread remains closely to the value at injection. In addition to the improved energy spread the beam stability of few-turn recirculators can be increased as well using such a system. We will present operational experience with the non-isochronous recirculation system of the twice recirculating superconducting accelerator S-DALINAC operated at TU Darmstadt including beam-dynamics calculations and measurements of the energy spread.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB004
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Paper

Title

Page

Time Resolved Cryogenic Cooling Analysis of the Cornell Injector Cryomodule

2298

R.G. Eichhorn, A.C. Bartnik, B.M. Dunham, G.M. Ge, G.H. Hoffstaetter, H. Lee, M. Liepe, S.R. Markham, T.I. O'Connell, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

To demonstrate key parameters of a an energy recovery linac (ERL) at Cornel, an injector based on a photo gun and an SRF cryomodule was designed and built. The goal was to demonstrate high current generation while achieving low emittances. While the emittance goal has been reached, the current achieved so far is 75 mA. Even though this is a world record, it is still below the targeted 100 mA. While ramping up the current we observed excessive heating in the fundamental power coupler which we were able to track down to insufficient cooling of the 80 K intercepts. These intercepts are cooled by a stream of parallel cryogenic flows which we found to be unbalanced. In this paper we will review the finding, describe the analysis we did, modeling of the parallel flow and the modifications made to the module to overcome the heating.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR018

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WEPMR020

First Cool-down of the Cornell ERL Main Linac Cryo-Module

2305

R.G. Eichhorn, J.V. Conway, F. Furuta, G.M. Ge, D. Gonnella, T. Gruber, G.H. Hoffstaetter, J.J. Kaufman, M. Liepe, T.I. O'Connell, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Cornell University has finished building a 10 m long superconducting accelerator module as a prototype of the main linac of a proposed ERL facility. This module houses 6 superconducting cavities- operated at 1.8 K in continuous wave (CW) mode with a design field of 16 MV/m and a Quality factor of 2x10¹⁰. We wil shortly review the design and focus on reporting on the first cool-down of this module. We will giving data for various cool-down scenarios (fast/ slow), uniformity and performance

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR020

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WEPMR021

HOM Measurements for Cornell's High-current CW ERL Cryomodule

2309

F. Furuta, R.G. Eichhorn, G.M. Ge, D. Gonnella, G.H. Hoffstaetter, M. Liepe, P. Quigley, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

The main linac cryomodule (MLC) for the future energy-recovery linac (ERL) based synchrotron-light facility at Cornell had been designed, fabricated, and tested. It houses 6 SRF cavities with individual higher order-modes (HOMs)absorbers and one magnet/ BPM section. We will report the HOM study on MLC.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR021

Export •

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

WEPMR022

ERL Main Linac Cryomodule Cavity Performance and Effect of Thermal Cycling

2312

F. Furuta, J. Dobbins, R.G. Eichhorn, G.M. Ge, D. Gonnella, G.H. Hoffstaetter, M. Liepe, T.I. O'Connell, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Cornell has designed, fabricated, and tested a high current (100 mA) CW SRF prototype cryomodule for the future energy-recovery linac (ERL) based synchrotron-light facility at Cornell . It houses six 7-cell SRF cavities with individual HOM absorbers and one magnet/ BPM section. Cavities are targeted to operate with high Qo of 2.0·10¹⁰ at 16.2 MV/m, 1.8 K in continuous wave (CW) mode. We will report the RF test results of 7-cell cavities in this cryomodule after initial cooldown and several thermal cycles with different cooldown method.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR022

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WEPMR025

Improved N-Doping Protocols for SRF Cavities

2323

D. Gonnella, R.G. Eichhorn, F. Furuta, G.M. Ge, T. Gruber, G.H. Hoffstaetter, J.J. Kaufman, P.N. Koufalis, M. Liepe, J.T. Maniscalco
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: NSF, DOE
Nitrogen-doping has been shown to consistently produce better quality factors in SRF cavities than is achievable with standard preparation techniques. Unfortunately, nitrogen-doping typically brings with it lower quench fields and higher sensitivities of residual resistance to trapped magnetic flux. Here we present work to understand these effects in hopes of mitigating them while maintaining the high Q desired by future projects. Using a nitrogen diffusion simulation, material parameters of nitrogen-doped cavities can be predicted prior to doping. These simulations results are consistent with SIMS data taken from samples treated with cavities. The nature of doping's effect on quench field has also been studied using CW and pulsed measurements. These results have allowed us to better understand the nature of nitrogen-doping and its effect on cavity performance.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR025

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THPMB004

Improving Energy Spread and Stability of a Recirculating Few-turn Linac

3222

F. Hug
IKP, Mainz, Germany
M. Arnold, T. Kürzeder, N. Pietralla
TU Darmstadt, Darmstadt, Germany
R.G. Eichhorn
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Supported by the DFG through CRC 634, RTG 2128 and PRISMA cluster of excellence
A non-isochronous recirculation scheme which helps cancelling out errors coming from the RF-jitters in a recirculating linac will be presented. Non-isochronous recirculation is the common operation mode for synchrotrons or microtrons. In such a scheme the recirculation arcs provide a non-zero longitudinal dispersion, while the particle bunches are accelerated at a certain phase off-crest with respect to the maximum of the accelerating field. In few-turn linacs and microtrons such beam dynamics can be used to reduce the energy spread. To do so the longitudinal phase advance needs to be set to a half-integer number of oscillations in phase space. Then errors from linac RF-systems cancel out and the energy spread remains closely to the value at injection. In addition to the improved energy spread the beam stability of few-turn recirculators can be increased as well using such a system. We will present operational experience with the non-isochronous recirculation system of the twice recirculating superconducting accelerator S-DALINAC operated at TU Darmstadt including beam-dynamics calculations and measurements of the energy spread.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB004

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