SRF2013 - List of Authors (Rimmer, R.A.)

Paper

Title

Page

A Summary of the Advanced Photon Source (APS) Short Pulse X-ray (SPX) R&D Accomplishments

92

A. Nassiri, N.D. Arnold, T.G. Berenc, M. Borland, B. Brajuskovic, D.J. Bromberek, J. Carwardine, G. Decker, L. Emery, J.D. Fuerst, J.P. Holzbauer, D. Horan, J.A. Kaluzny, J.S. Kerby, F. Lenkszus, R.M. Lill, H. Ma, V. Sajaev, B.K. Stillwell, G.J. Waldschmidt, M. White, G. Wu, Y. Yang, A. Zholents
ANL, Argonne, USA
J.M. Byrd, L.R. Doolittle, G. Huang
LBNL, Berkeley, California, USA
P. Dhakal, J. Henry, J.D. Mammosser, J. Matalevich, R.A. Rimmer, H. Wang, K.M. Wilson
JLAB, Newport News, Virginia, USA
Z. Li, L. Xiao
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06H11357.
The Advanced Photon Source Upgrade Project (APS-U) at Argonne will include generation of short-pulse x-rays based on Zholents’ [1] deflecting cavity scheme. We have chosen superconducting (SC) cavities in order to have a continuous train of crabbed bunches and flexibility of operating modes. Since early 2012, in collaboration with Jefferson National Laboratory, we have made significant progress prototyping and testing a number of single-cell deflecting cavities. We have designed, prototyped, and tested silicon carbide as damping material for higher-order-mode (HOM) dampers, which are broadband to handle the HOM power across the frequency spectrum produced by the APS beam. In collaboration with Lawrence Berkeley National Laboratory, we have developing a state-of-the-art timing and synchronization system for distributing stable rf signals over optical fiber capable of achieving tens of femtoseconds phase drift and jitter. Collaboration with the Advanced Computations Department at Stanford Linear Accelerator Center is looking into simulations of complex, multi- cavity geometries. This contribution provides a progress report on the current R&D status of the SPX project.
[1] A. Zholents et al., NIM A 425, 385 (1999).

MOP019

Comparison of Linacs for Small-Scale Inverse Compton Scattering Light Source Applications

F.S. He, F.E. Hannon, J.D. Mammosser, R.A. Rimmer, H. Wang
JLAB, Newport News, Virginia, USA

Funding: Work supported by DOE
Great interest has been generated by the possibility of compact, high brilliance X-ray source based on inverse Compton scattering (ICS) since the rapid advancement in laser and accelerator technologies. While most superconducting (SC) linac designs have been aimed at large high energy facilities throughout the world, a compact and affordable SC linac that fits compact ICS source would be very attractive. MIT had proposed such concept, but the linac for electron acceleration after injector was not well defined then. JLab is developing the concept of a compact cryostat, which contains two elliptical, 400MHz, 3-cell cavities, to demonstrate the SRF technology for ICS applications. The linac is designed to accelerate an electron beam with a bunch charge of 5 pC at 200 MHz repetition rate, increasing the energy by 17 MeV. SC elliptical cavities at various frequencies, SC spoke cavity with β=1, and normal conducting (NC) cavities were compared in order to minimize the dynamic heat load. In this paper, the performance, capital and operational cost are compared among different options, and the choice of JLab is justified.

Slides MOP019 [0.846 MB]

MOP077

Cryomodule Component Development for the APS Upgrade Short Pulse X-Ray Project

314

J.P. Holzbauer, J.D. Fuerst, A. Nassiri, Y. Shiroyanagi, B.K. Stillwell, G.J. Waldschmidt, G. Wu
ANL, Argonne, USA
G. Cheng, J. Henry, J.D. Mammosser, J. Matalevich, J.P. Preble, R.A. Rimmer, H. Wang, K.M. Wilson, M. Wiseman, S. Yang
JLAB, Newport News, Virginia, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CHI1357 at ANL and under U.S. DOE Contract No. DE-AC05-06OR23177 at Jefferson Lab.
The short pulse x-ray (SPX) part of the Advanced Photon Source Upgrade calls for the installation of a two-cavity cryomodule in the APS ring to study cavity-beam interaction, including HOM damping and cavity timing and synchronization. Design of this cryomodule is underway at Jefferson Lab in collaboration with the APS Upgrade team at ANL. The cryomodule design faces several challenges including tight spacing to fit in the APS ring, a complex set of cavity waveguides including HOM waveguides and dampers enclosed in the insulating vacuum space, and tight alignment tolerances due to the APS high beam-current (up to 150 mA). Given these constraints, special focus has been put on modifying existing CEBAF-style designs, including a cavity tuner and alignment scheme, to accommodate these challenges. The thermal design has also required extensive work including coupled thermal-mechanical simulations to determine the effects of cool-down on both alignment and waveguides. This work will be presented and discussed in this paper.

TUP095

Field Emission and Consequences as Observed and Simulated for CEBAF Upgrade Cryomodules

694

F. Marhauser, R.P. Johnson, R. Rodriguez
Muons, Inc, Illinois, USA
P. Degtiarenko, A. Hutton, G. Kharashvili, C.E. Reece, R.A. Rimmer
JLAB, Newport News, Virginia, USA

High gamma and neutron radiation levels were monitored at the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Laboratory (JLab) after installation of new cavity cryomodules and initial test runs in the frame of the ongoing 12 GeV upgrade program. The dose rates scaled exponentially with cavity accelerating fields, but were independent of the presence of an electron beam in the accelerator. Hence, field emission (FE) is the source of origin. This has led to concerns regarding the high field operation (100 MV per cryomodule) in the future 12 GeV era. Utilizing supercomputing, novel FE studies have been performed with electrons tracked through a complete cryomodule. It provides a principal understanding of experimental observations as well as ways to mitigate FE as best as practicable by identification of problematic cavities.

THIOB01

CEBAF Upgrade: Cryomodule Performance and Lessons Learned

836

M.A. Drury, J. Hogan, C. Hovater, L.K. King, H. Park, J.P. Preble, R.A. Rimmer, H. Wang, M. Wiseman
JLAB, Newport News, Virginia, USA
G.K. Davis, C.E. Reece
JLab, Newport News, Virginia, USA
F. Marhauser
Muons, Inc, Illinois, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract DE-AC05-06OR23177.
The Thomas Jefferson National Accelerator Facility is currently engaged in the 12 GeV Upgrade Project. The goal of the 12 GeV Upgrade is a doubling of the available beam energy of the Continuous Electron Beam Accelerator Facility (CEBAF) from 6 GeV to 12 GeV. The increase in beam energy will largely be due to the addition of ten C100 cryomodules and the associated RF in the CEBAF linacs. These cryomodules are designed to deliver 100 MeV per cryomodule. Each C100 cryomodule contains a string of eight seven-cell, electro-polished, superconducting RF cavities. While an average performance of 100 MV is needed to achieve the overall 12 GeV beam energy goal, the actual performance goal for the cryomodules is an average energy gain of 108 MV to provide operational headroom. All ten of the C100 cryomodules are installed in the linac tunnels and are on schedule to be commissioned by September 2013. Commissioned performance has ranged from 104 MV to 118 MV. In May, 2012, a test of an early C100 achieved 108 MV with full beam loading. This paper will discuss the performance of the C100 cryomodules along with operational challenges and lessons learned for future designs.
The U.S. Govt. retains a non-exclusive, paid-up,irrevocable,world-wide license to publish or reproduce this manuscript.

Slides THIOB01 [2.534 MB]

THP013

A New Cavity Design for Medium Beta Acceleration

920

F.S. He, R.A. Rimmer, H. Wang
JLAB, Newport News, Virginia, USA

Funding: Work supported by DOE
Heavy duty or CW, superconducting proton and heavy ion accelerators are being proposed and constructed worldwide. The total length of the machine is one of the main drivers in terms of cost. Thus HWR and spoke cavities at medium beta are usually optimized to achieve low surface field and high gradient. A novel accelerating structure at β=0.5 evolved from spoke cavity is proposed, with lower surface fields but slightly higher heat load. It would be an interesting option for pulsed and CW accelerators with beam energy of more than 200MeV/u.

THP014

A Prototype Cavity for Inverse Compton Scattering Light Source Applications

F.S. He, G. Cheng, W.A. Clemens, J. Henry, P. Kneisel, B.R. Lang, J.D. Mammosser, R.A. Rimmer, G. Slack, C. Tennant, L. Turlington, H. Wang, S. Yang
JLAB, Newport News, Virginia, USA

Funding: Work supported by DOE
Compact, high brilliance X-ray sources, based on inverse Compton scattering (ICS), have gained enormous interest worldwide. A compact and affordable superconducting (SC) linac is one of the key components of such applications. JLab is developing the concept of a compact cryostat, which contains two elliptical, 400MHz, 3-cell cavities, to demonstrate the SRF technology for ICS application. In this paper, the RF optimization, HOM criteria, mechanical analysis, fabrication experience and the test result of the prototype cavity are reported.

Slides THP014 [2.718 MB]

FRIOA03

Fabrication and Testing of Deflecting Cavities for APS

1170

J.D. Mammosser
JLab, Newport News, Virginia, USA
P. Dhakal, J. Henry, R.A. Rimmer, H. Wang, K.M. Wilson
JLAB, Newport News, Virginia, USA
J.F. Fuerst, J.P. Holzbauer, J.S. Kerby, A. Nassiri, G.J. Waldschmidt, G. Wu, Y. Yang
ANL, Argonne, USA
F. He
PKU, Beijing, People's Republic of China
Z. Li
SLAC, Menlo Park, California, USA

Abstract Jefferson Lab in Newport News, Virginia, in collaboration with Argonne National Laboratory, Argonne, Il, has fabricated and tested three production, 2.815 GHz crab cavities for Argonne’s Short-Pulse X-ray project. These cavities are unique in that the cavity and waveguides were milled from bulk large grain niobium ingot material directly from 3D CAD files. No forming of sub components was used with the exception of the beam-pipes. The cavity and helium vessel design along with the RF performance requirements makes this project extremely challenging for fabrication. Production challenges and fabrication techniques as well as testing results will be discussed in this paper.

Slides FRIOA03 [22.677 MB]

Paper	Title	Page
MOP009	A Summary of the Advanced Photon Source (APS) Short Pulse X-ray (SPX) R&D Accomplishments	92
	A. Nassiri, N.D. Arnold, T.G. Berenc, M. Borland, B. Brajuskovic, D.J. Bromberek, J. Carwardine, G. Decker, L. Emery, J.D. Fuerst, J.P. Holzbauer, D. Horan, J.A. Kaluzny, J.S. Kerby, F. Lenkszus, R.M. Lill, H. Ma, V. Sajaev, B.K. Stillwell, G.J. Waldschmidt, M. White, G. Wu, Y. Yang, A. Zholents ANL, Argonne, USA J.M. Byrd, L.R. Doolittle, G. Huang LBNL, Berkeley, California, USA P. Dhakal, J. Henry, J.D. Mammosser, J. Matalevich, R.A. Rimmer, H. Wang, K.M. Wilson JLAB, Newport News, Virginia, USA Z. Li, L. Xiao SLAC, Menlo Park, California, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06H11357. The Advanced Photon Source Upgrade Project (APS-U) at Argonne will include generation of short-pulse x-rays based on Zholents’ [1] deflecting cavity scheme. We have chosen superconducting (SC) cavities in order to have a continuous train of crabbed bunches and flexibility of operating modes. Since early 2012, in collaboration with Jefferson National Laboratory, we have made significant progress prototyping and testing a number of single-cell deflecting cavities. We have designed, prototyped, and tested silicon carbide as damping material for higher-order-mode (HOM) dampers, which are broadband to handle the HOM power across the frequency spectrum produced by the APS beam. In collaboration with Lawrence Berkeley National Laboratory, we have developing a state-of-the-art timing and synchronization system for distributing stable rf signals over optical fiber capable of achieving tens of femtoseconds phase drift and jitter. Collaboration with the Advanced Computations Department at Stanford Linear Accelerator Center is looking into simulations of complex, multi- cavity geometries. This contribution provides a progress report on the current R&D status of the SPX project. [1] A. Zholents et al., NIM A 425, 385 (1999).

MOP019	Comparison of Linacs for Small-Scale Inverse Compton Scattering Light Source Applications
	F.S. He, F.E. Hannon, J.D. Mammosser, R.A. Rimmer, H. Wang JLAB, Newport News, Virginia, USA
	Funding: Work supported by DOE Great interest has been generated by the possibility of compact, high brilliance X-ray source based on inverse Compton scattering (ICS) since the rapid advancement in laser and accelerator technologies. While most superconducting (SC) linac designs have been aimed at large high energy facilities throughout the world, a compact and affordable SC linac that fits compact ICS source would be very attractive. MIT had proposed such concept, but the linac for electron acceleration after injector was not well defined then. JLab is developing the concept of a compact cryostat, which contains two elliptical, 400MHz, 3-cell cavities, to demonstrate the SRF technology for ICS applications. The linac is designed to accelerate an electron beam with a bunch charge of 5 pC at 200 MHz repetition rate, increasing the energy by 17 MeV. SC elliptical cavities at various frequencies, SC spoke cavity with β=1, and normal conducting (NC) cavities were compared in order to minimize the dynamic heat load. In this paper, the performance, capital and operational cost are compared among different options, and the choice of JLab is justified.
	Slides MOP019 [0.846 MB]

MOP077	Cryomodule Component Development for the APS Upgrade Short Pulse X-Ray Project	314
	J.P. Holzbauer, J.D. Fuerst, A. Nassiri, Y. Shiroyanagi, B.K. Stillwell, G.J. Waldschmidt, G. Wu ANL, Argonne, USA G. Cheng, J. Henry, J.D. Mammosser, J. Matalevich, J.P. Preble, R.A. Rimmer, H. Wang, K.M. Wilson, M. Wiseman, S. Yang JLAB, Newport News, Virginia, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CHI1357 at ANL and under U.S. DOE Contract No. DE-AC05-06OR23177 at Jefferson Lab. The short pulse x-ray (SPX) part of the Advanced Photon Source Upgrade calls for the installation of a two-cavity cryomodule in the APS ring to study cavity-beam interaction, including HOM damping and cavity timing and synchronization. Design of this cryomodule is underway at Jefferson Lab in collaboration with the APS Upgrade team at ANL. The cryomodule design faces several challenges including tight spacing to fit in the APS ring, a complex set of cavity waveguides including HOM waveguides and dampers enclosed in the insulating vacuum space, and tight alignment tolerances due to the APS high beam-current (up to 150 mA). Given these constraints, special focus has been put on modifying existing CEBAF-style designs, including a cavity tuner and alignment scheme, to accommodate these challenges. The thermal design has also required extensive work including coupled thermal-mechanical simulations to determine the effects of cool-down on both alignment and waveguides. This work will be presented and discussed in this paper.

TUP095	Field Emission and Consequences as Observed and Simulated for CEBAF Upgrade Cryomodules	694
	F. Marhauser, R.P. Johnson, R. Rodriguez Muons, Inc, Illinois, USA P. Degtiarenko, A. Hutton, G. Kharashvili, C.E. Reece, R.A. Rimmer JLAB, Newport News, Virginia, USA
	High gamma and neutron radiation levels were monitored at the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Laboratory (JLab) after installation of new cavity cryomodules and initial test runs in the frame of the ongoing 12 GeV upgrade program. The dose rates scaled exponentially with cavity accelerating fields, but were independent of the presence of an electron beam in the accelerator. Hence, field emission (FE) is the source of origin. This has led to concerns regarding the high field operation (100 MV per cryomodule) in the future 12 GeV era. Utilizing supercomputing, novel FE studies have been performed with electrons tracked through a complete cryomodule. It provides a principal understanding of experimental observations as well as ways to mitigate FE as best as practicable by identification of problematic cavities.

THIOB01	CEBAF Upgrade: Cryomodule Performance and Lessons Learned	836
	M.A. Drury, J. Hogan, C. Hovater, L.K. King, H. Park, J.P. Preble, R.A. Rimmer, H. Wang, M. Wiseman JLAB, Newport News, Virginia, USA G.K. Davis, C.E. Reece JLab, Newport News, Virginia, USA F. Marhauser Muons, Inc, Illinois, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract DE-AC05-06OR23177. The Thomas Jefferson National Accelerator Facility is currently engaged in the 12 GeV Upgrade Project. The goal of the 12 GeV Upgrade is a doubling of the available beam energy of the Continuous Electron Beam Accelerator Facility (CEBAF) from 6 GeV to 12 GeV. The increase in beam energy will largely be due to the addition of ten C100 cryomodules and the associated RF in the CEBAF linacs. These cryomodules are designed to deliver 100 MeV per cryomodule. Each C100 cryomodule contains a string of eight seven-cell, electro-polished, superconducting RF cavities. While an average performance of 100 MV is needed to achieve the overall 12 GeV beam energy goal, the actual performance goal for the cryomodules is an average energy gain of 108 MV to provide operational headroom. All ten of the C100 cryomodules are installed in the linac tunnels and are on schedule to be commissioned by September 2013. Commissioned performance has ranged from 104 MV to 118 MV. In May, 2012, a test of an early C100 achieved 108 MV with full beam loading. This paper will discuss the performance of the C100 cryomodules along with operational challenges and lessons learned for future designs. The U.S. Govt. retains a non-exclusive, paid-up,irrevocable,world-wide license to publish or reproduce this manuscript.
	Slides THIOB01 [2.534 MB]

THP013	A New Cavity Design for Medium Beta Acceleration	920
	F.S. He, R.A. Rimmer, H. Wang JLAB, Newport News, Virginia, USA
	Funding: Work supported by DOE Heavy duty or CW, superconducting proton and heavy ion accelerators are being proposed and constructed worldwide. The total length of the machine is one of the main drivers in terms of cost. Thus HWR and spoke cavities at medium beta are usually optimized to achieve low surface field and high gradient. A novel accelerating structure at β=0.5 evolved from spoke cavity is proposed, with lower surface fields but slightly higher heat load. It would be an interesting option for pulsed and CW accelerators with beam energy of more than 200MeV/u.

THP014	A Prototype Cavity for Inverse Compton Scattering Light Source Applications
	F.S. He, G. Cheng, W.A. Clemens, J. Henry, P. Kneisel, B.R. Lang, J.D. Mammosser, R.A. Rimmer, G. Slack, C. Tennant, L. Turlington, H. Wang, S. Yang JLAB, Newport News, Virginia, USA
	Funding: Work supported by DOE Compact, high brilliance X-ray sources, based on inverse Compton scattering (ICS), have gained enormous interest worldwide. A compact and affordable superconducting (SC) linac is one of the key components of such applications. JLab is developing the concept of a compact cryostat, which contains two elliptical, 400MHz, 3-cell cavities, to demonstrate the SRF technology for ICS application. In this paper, the RF optimization, HOM criteria, mechanical analysis, fabrication experience and the test result of the prototype cavity are reported.
	Slides THP014 [2.718 MB]

FRIOA03	Fabrication and Testing of Deflecting Cavities for APS	1170
	J.D. Mammosser JLab, Newport News, Virginia, USA P. Dhakal, J. Henry, R.A. Rimmer, H. Wang, K.M. Wilson JLAB, Newport News, Virginia, USA J.F. Fuerst, J.P. Holzbauer, J.S. Kerby, A. Nassiri, G.J. Waldschmidt, G. Wu, Y. Yang ANL, Argonne, USA F. He PKU, Beijing, People's Republic of China Z. Li SLAC, Menlo Park, California, USA
	Abstract Jefferson Lab in Newport News, Virginia, in collaboration with Argonne National Laboratory, Argonne, Il, has fabricated and tested three production, 2.815 GHz crab cavities for Argonne’s Short-Pulse X-ray project. These cavities are unique in that the cavity and waveguides were milled from bulk large grain niobium ingot material directly from 3D CAD files. No forming of sub components was used with the exception of the beam-pipes. The cavity and helium vessel design along with the RF performance requirements makes this project extremely challenging for fabrication. Production challenges and fabrication techniques as well as testing results will be discussed in this paper.
	Slides FRIOA03 [22.677 MB]