SRF2013 - List of Authors (Mammosser, J.D.)

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.

MOP078

Horizontal Testing of a Dressed Deflecting Mode Cavity for the APS Upgrade Short Pulse X-Ray Project

321

J.P. Holzbauer, N.D. Arnold, T.G. Berenc, D.J. Bromberek, J. Carwardine, N.P. Di Monte, J.D. Fuerst, A.E. Grelick, D. Horan, J.A. Kaluzny, J.W. Lang, H. Ma, T.L. Mann, D.A. Meyer, M.E. Middendorf, A. Nassiri, Y. Shiroyanagi, J.H. Vacca, G.J. Waldschmidt, R.D. Wright, G. Wu, Y. Yang, A. Zholents
ANL, Argonne, USA
E.R. Harms, W. Schappert
Fermilab, Batavia, USA
J.D. Mammosser
JLAB, Newport News, Virginia, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CHI1357.
The short pulse x-ray (SPX) part of the Advanced Photon Source (APS) Upgrade is an effort to enhance time-resolved experiments on a few-ps-scale at the APS. The goal of SPX is the generation of short pulses of x-rays for pump-probe time-resolved capability using superconducting rf (SRF) deflecting cavities*. These cavities will create a correlation between longitudinal position in the electron bunch and vertical momentum**. The light produced by this bunch can be passed through a slit to produce a pulse of light much shorter (1-2 ps instead of 100 ps) than the bunch length at reduced flux. An SPX cavity has been tested with a helium vessel and tuner. In addition to studying rf performance with more realistic cooling, this test allowed integration and operation of many systems designed for SPX cryomodule in-ring operation. These systems included an APS-constructed 5 kW, 2.815 GHz amplifier, a digital low-level rf controller system designed and fabricated in collaboration with LBNL, a cavity tuner, and instrumentation systems designed for the existing APS infrastructure. Cavity performance and subsystem performance will be reported and discussed in this paper.
* A. Zholents et al., NIM A 425, 385 (1999).
** A. Nassiri et al., “Status of the Short-Pulse X-Ray Project at the Advanced Photon Source,” IPAC 2012, New Orleans, LA, May 2012.

TUP055

Electropolishing of the ANL Deflecting Cavity for the APS Upgrade

544

Y. Yang, J.D. Fuerst, J.P. Holzbauer, J.A. Kaluzny, A. Nassiri, G. Wu
ANL, Argonne, USA
A.C. Crawford
Fermilab, Batavia, USA
P. Dhakal, J.D. Mammosser, H. Wang
JLAB, Newport News, Virginia, USA
Y. Yang
TUB, Beijing, People's Republic of China

Studies on the application of electropolishing (EP) of the ANL superconducting deflecting cavity have shown promising results. This cavity geometry is a squashed single-cell cavity with Y-end group waveguide as well as on-cell LOM damper. The cavity works at TM110-like deflecting mode, in which the iris between the cavity cell and the Y-end group is the highest magnetic field region. Before EP, the cavity had been chemically etched (BCP) several times. Forty-um EP processing was performed on one Mark II prototype deflecting cavity at Fermilab. No mild baking was performed before the cavity vertical test. The test showed that the low-field Q had improved from 2·10⁹ to 3·10⁹ and the high-field Q-slope had been successfully removed. The quench limit was slightly improved from 10⁶ mT to 113 mT. Fast T-mapping had detected a significant decrease of local temperature rise in the cavity iris. Optical inspection before EP found a lot of grooves around the iris, which might be related to the gas bubbles generated during BCP. This suggests that horizontal EP is a promising processing technique to remove the high-field Q-slope and improve the deflecting cavity performance.

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.

MOP078	Horizontal Testing of a Dressed Deflecting Mode Cavity for the APS Upgrade Short Pulse X-Ray Project	321
	J.P. Holzbauer, N.D. Arnold, T.G. Berenc, D.J. Bromberek, J. Carwardine, N.P. Di Monte, J.D. Fuerst, A.E. Grelick, D. Horan, J.A. Kaluzny, J.W. Lang, H. Ma, T.L. Mann, D.A. Meyer, M.E. Middendorf, A. Nassiri, Y. Shiroyanagi, J.H. Vacca, G.J. Waldschmidt, R.D. Wright, G. Wu, Y. Yang, A. Zholents ANL, Argonne, USA E.R. Harms, W. Schappert Fermilab, Batavia, USA J.D. Mammosser JLAB, Newport News, Virginia, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CHI1357. The short pulse x-ray (SPX) part of the Advanced Photon Source (APS) Upgrade is an effort to enhance time-resolved experiments on a few-ps-scale at the APS. The goal of SPX is the generation of short pulses of x-rays for pump-probe time-resolved capability using superconducting rf (SRF) deflecting cavities. These cavities will create a correlation between longitudinal position in the electron bunch and vertical momentum. The light produced by this bunch can be passed through a slit to produce a pulse of light much shorter (1-2 ps instead of 100 ps) than the bunch length at reduced flux. An SPX cavity has been tested with a helium vessel and tuner. In addition to studying rf performance with more realistic cooling, this test allowed integration and operation of many systems designed for SPX cryomodule in-ring operation. These systems included an APS-constructed 5 kW, 2.815 GHz amplifier, a digital low-level rf controller system designed and fabricated in collaboration with LBNL, a cavity tuner, and instrumentation systems designed for the existing APS infrastructure. Cavity performance and subsystem performance will be reported and discussed in this paper. A. Zholents et al., NIM A 425, 385 (1999). ** A. Nassiri et al., “Status of the Short-Pulse X-Ray Project at the Advanced Photon Source,” IPAC 2012, New Orleans, LA, May 2012.

TUP055	Electropolishing of the ANL Deflecting Cavity for the APS Upgrade	544
	Y. Yang, J.D. Fuerst, J.P. Holzbauer, J.A. Kaluzny, A. Nassiri, G. Wu ANL, Argonne, USA A.C. Crawford Fermilab, Batavia, USA P. Dhakal, J.D. Mammosser, H. Wang JLAB, Newport News, Virginia, USA Y. Yang TUB, Beijing, People's Republic of China
	Studies on the application of electropolishing (EP) of the ANL superconducting deflecting cavity have shown promising results. This cavity geometry is a squashed single-cell cavity with Y-end group waveguide as well as on-cell LOM damper. The cavity works at TM110-like deflecting mode, in which the iris between the cavity cell and the Y-end group is the highest magnetic field region. Before EP, the cavity had been chemically etched (BCP) several times. Forty-um EP processing was performed on one Mark II prototype deflecting cavity at Fermilab. No mild baking was performed before the cavity vertical test. The test showed that the low-field Q had improved from 2·10⁹ to 3·10⁹ and the high-field Q-slope had been successfully removed. The quench limit was slightly improved from 10⁶ mT to 113 mT. Fast T-mapping had detected a significant decrease of local temperature rise in the cavity iris. Optical inspection before EP found a lot of grooves around the iris, which might be related to the gas bubbles generated during BCP. This suggests that horizontal EP is a promising processing technique to remove the high-field Q-slope and improve the deflecting cavity performance.

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]