IPAC2015 - List of Authors (Moretti, A.)

Paper	Title	Page
MOAD2	RF Breakdown of 805 MHz Cavities in Strong Magnetic Fields	53
	D.L. Bowring, A.V. Kochemirovskiy, M.A. Leonova, A. Moretti, M.A. Palmer, D.W. Peterson, K. Yonehara Fermilab, Batavia, Illinois, USA B.T. Freemire IIT, Chicago, Illinois, USA A.A. Haase SLAC, Menlo Park, California, USA P.G. Lane, Y. Torun Illinois Institute of Technology, Chicago, Illlinois, USA D. Stratakis BNL, Upton, Long Island, New York, USA
	Ionization cooling of intense muon beams requires the operation of high-gradient, normal-conducting RF structures in the presence of strong magnetic fields. We have measured the breakdown rate in several RF cavities operating at several frequencies. Cavities operating within solenoidal magnetic fields B > 0.25 T show an increased RF breakdown rate at lower gradients compared with similar operation when B = 0 T. Ultimately, this breakdown behavior limits the maximum safe operating gradient of the cavity. Beyond ionization cooling, this issue affects the design of photoinjectors and klystrons, among other applications. We have built an 805 MHz pillbox-type RF cavity to serve as an experimental testbed for this phenomenon. This cavity is designed to study the problem of RF breakdown in strong magnetic fields using various cavity materials and surface treatments, and with precise control over sources of systematic error. We present results from tests in which the cavity was run with all copper surfaces in a variety of magnetic fields.
	Slides MOAD2 [10.792 MB]
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WEPTY030	Breakdown Characterization in 805 MHz Pillbox-like Cavity in Strong Magnetic Fields	3335
	A.V. Kochemirovskiy, D.L. Bowring, A. Moretti, D.W. Peterson, K. Yonehara Fermilab, Batavia, Illinois, USA M. Chung UNIST, Ulsan, Republic of Korea G. Flanagan, G.M. Kazakevich Muons, Inc, Illinois, USA B.T. Freemire IIT, Chicago, Illinois, USA A.V. Kochemirovskiy University of Chicago, Chicago, Illinois, USA Y. Torun Illinois Institute of Technology, Chicago, Illlinois, USA
	RF Breakdown in strong magnetic fields has a negative impact on a cavity performance. The MuCool Test Area at Fermilab has unique capabilities that that allow us to study the effects of static magnetic field on RF cavity operation. We have tested an 805 MHz pillbox-like cavity in external magnetic fields up to 5T. Results confirm our basic model of breakdown in strong magnetic fields. We have measured maximum achievable surface gradient dependence on external static magnetic field. Damage inspection of cavity walls revealed a unique observed breakdown pattern. We present the analysis of breakdown damage distribution and propose the hypothesis to explain certain features of this distribution
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY030
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WEPTY032	MICE Cavity Installation and Commissioning/Operation at MTA	3342
	M.A. Leonova, M. Backfish, D.L. Bowring, A.V. Kochemirovskiy, A. Moretti, D.W. Peterson, M. Popovic, Y. Torun, K. Yonehara Fermilab, Batavia, Illinois, USA B.T. Freemire IIT, Chicago, Illinois, USA C. Hunt Imperial College of Science and Technology, Department of Physics, London, United Kingdom P.G. Lane Illinois Institute of Technology, Chicago, Illinois, USA T.H. Luo LBNL, Berkeley, California, USA D.C. Speirs, C.G. Whyte USTRAT/SUPA, Glasgow, United Kingdom T. Stanley STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
	A first electropolished 201-MHz RF cavity for the international Muon Ionization Cooling Experiment (MICE) has been assembled inside a special vacuum vessel and installed at the Fermilab's MuCool Test Area (MTA). The cavity and the MTA hall have been equipped with numerous instrumentation to characterize cavity operation. The cavity has been commissioned to run at 14 MV/m gradient with no external magnetic field; it is also being commissioned in presence of fringe field of a multi-Tesla superconducting solenoid magnet, the condition in which cavity modules will be operated in the MICE cooling channel. The assembly, installation and operation of the Single-Cavity Module gave valuable experience for operation of full-size modules at MICE.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY032
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WEPTY050	Low Powered RF Measurements of Dielectric Materials for use in High Pressure Gas Filled RF Cavities	3387
	B.T. Freemire IIT, Chicago, Illinois, USA G. Arriaga Northern Illinois Univerity, Dekalb, Illinois, USA D.L. Bowring, A.V. Kochemirovskiy, A. Moretti, A.V. Tollestrup, Y. Torun, K. Yonehara Fermilab, Batavia, Illinois, USA H.D. Phan McDaniel College, Westminster, USA Y. Torun Illinois Institute of Technology, Chicago, Illlinois, USA
	The Helical Cooling Channel scheme envisioned for a Muon Collider or Neutrino Factory requires high pressure gas filled radio frequency cavities to operate in superconducting magnets. One method to shrink the radii of the cavities is to load them with a dielectric material. The dielectric constant, loss tangent, and dielectric strength are important in determining the most suitable material. Low powered RF measurements of the dielectric constant and loss tangent were taken for multiple purities of alumina and magnesium calcium titanate, as well as cordierite, forsterite, and aluminum nitride. Measurements of alumina were consistent with previously reported results. The results were used to design an insert for a high powered RF test that included sending beam through the cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY050
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WEPTY054	Grid Window Tests on an 805-MHz Pillbox Cavity	3393
	Y. Torun Illinois Institute of Technology, Chicago, Illlinois, USA A. Moretti Fermilab, Batavia, Illinois, USA
	Funding: Supported by the US Department of Energy Office of Science through the Muon Accelerator Program. Muon ionization cooling channel designs use pillbox shaped RF cavities for improved power efficiency and fine control over phasing of individual cavities. For minimum scattering of the muon beam, the ends should be made out of a small thickness of high radiation length material. Good electrical and thermal conductivity are required to reduce power dissipation and remove the heat efficiently. Thin curved beryllium windows with TiN coating have been used successfully in the past. We have built an alternative window set consisting of grids of tubes and tested these on a pillbox cavity previously used with both thin Be and thick Cu windows. The cavity was operated with a pair of grids as well as a single grid against a flat endplate.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY054
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WEPTY055	Installation and Commissioning of the MICE RF Module Prototype	3395
	Y. Torun, P.G. Lane Illinois Institute of Technology, Chicago, Illinois, USA T.G. Anderson, D.L. Bowring, M. Chung, J.H. Gaynier, M.A. Leonova, A. Moretti, R.J. Pasquinelli, D.W. Peterson, R.P. Schultz Fermilab, Batavia, Illinois, USA A.J. DeMello, D. Li, S.P. Virostek LBNL, Berkeley, California, USA L. Somaschini INFN-Pisa, Pisa, Italy
	Funding: Supported by the US Department of Energy Office of Science through the Muon Accelerator Program. A special vacuum vessel prototype was built to house the first production 201 MHz RF cavity for the International Muon Ionization Cooling Experiment (MICE). The resulting prototype RF module has been assembled, instrumented, installed and commissioned at Fermilab's MuCool Test Area and the effort has provided valuable experience for the design of modules that will be used in the cooling channel for the experiment.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY055
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Paper

Title

Page

RF Breakdown of 805 MHz Cavities in Strong Magnetic Fields

53

D.L. Bowring, A.V. Kochemirovskiy, M.A. Leonova, A. Moretti, M.A. Palmer, D.W. Peterson, K. Yonehara
Fermilab, Batavia, Illinois, USA
B.T. Freemire
IIT, Chicago, Illinois, USA
A.A. Haase
SLAC, Menlo Park, California, USA
P.G. Lane, Y. Torun
Illinois Institute of Technology, Chicago, Illlinois, USA
D. Stratakis
BNL, Upton, Long Island, New York, USA

Ionization cooling of intense muon beams requires the operation of high-gradient, normal-conducting RF structures in the presence of strong magnetic fields. We have measured the breakdown rate in several RF cavities operating at several frequencies. Cavities operating within solenoidal magnetic fields B > 0.25 T show an increased RF breakdown rate at lower gradients compared with similar operation when B = 0 T. Ultimately, this breakdown behavior limits the maximum safe operating gradient of the cavity. Beyond ionization cooling, this issue affects the design of photoinjectors and klystrons, among other applications. We have built an 805 MHz pillbox-type RF cavity to serve as an experimental testbed for this phenomenon. This cavity is designed to study the problem of RF breakdown in strong magnetic fields using various cavity materials and surface treatments, and with precise control over sources of systematic error. We present results from tests in which the cavity was run with all copper surfaces in a variety of magnetic fields.

Slides MOAD2 [10.792 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOAD2

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WEPTY030

Breakdown Characterization in 805 MHz Pillbox-like Cavity in Strong Magnetic Fields

3335

A.V. Kochemirovskiy, D.L. Bowring, A. Moretti, D.W. Peterson, K. Yonehara
Fermilab, Batavia, Illinois, USA
M. Chung
UNIST, Ulsan, Republic of Korea
G. Flanagan, G.M. Kazakevich
Muons, Inc, Illinois, USA
B.T. Freemire
IIT, Chicago, Illinois, USA
A.V. Kochemirovskiy
University of Chicago, Chicago, Illinois, USA
Y. Torun
Illinois Institute of Technology, Chicago, Illlinois, USA

RF Breakdown in strong magnetic fields has a negative impact on a cavity performance. The MuCool Test Area at Fermilab has unique capabilities that that allow us to study the effects of static magnetic field on RF cavity operation. We have tested an 805 MHz pillbox-like cavity in external magnetic fields up to 5T. Results confirm our basic model of breakdown in strong magnetic fields. We have measured maximum achievable surface gradient dependence on external static magnetic field. Damage inspection of cavity walls revealed a unique observed breakdown pattern. We present the analysis of breakdown damage distribution and propose the hypothesis to explain certain features of this distribution

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY030

Export •

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

WEPTY032

MICE Cavity Installation and Commissioning/Operation at MTA

3342

M.A. Leonova, M. Backfish, D.L. Bowring, A.V. Kochemirovskiy, A. Moretti, D.W. Peterson, M. Popovic, Y. Torun, K. Yonehara
Fermilab, Batavia, Illinois, USA
B.T. Freemire
IIT, Chicago, Illinois, USA
C. Hunt
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
P.G. Lane
Illinois Institute of Technology, Chicago, Illinois, USA
T.H. Luo
LBNL, Berkeley, California, USA
D.C. Speirs, C.G. Whyte
USTRAT/SUPA, Glasgow, United Kingdom
T. Stanley
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

A first electropolished 201-MHz RF cavity for the international Muon Ionization Cooling Experiment (MICE) has been assembled inside a special vacuum vessel and installed at the Fermilab's MuCool Test Area (MTA). The cavity and the MTA hall have been equipped with numerous instrumentation to characterize cavity operation. The cavity has been commissioned to run at 14 MV/m gradient with no external magnetic field; it is also being commissioned in presence of fringe field of a multi-Tesla superconducting solenoid magnet, the condition in which cavity modules will be operated in the MICE cooling channel. The assembly, installation and operation of the Single-Cavity Module gave valuable experience for operation of full-size modules at MICE.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY032

Export •

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

WEPTY050

Low Powered RF Measurements of Dielectric Materials for use in High Pressure Gas Filled RF Cavities

3387

B.T. Freemire
IIT, Chicago, Illinois, USA
G. Arriaga
Northern Illinois Univerity, Dekalb, Illinois, USA
D.L. Bowring, A.V. Kochemirovskiy, A. Moretti, A.V. Tollestrup, Y. Torun, K. Yonehara
Fermilab, Batavia, Illinois, USA
H.D. Phan
McDaniel College, Westminster, USA
Y. Torun
Illinois Institute of Technology, Chicago, Illlinois, USA

The Helical Cooling Channel scheme envisioned for a Muon Collider or Neutrino Factory requires high pressure gas filled radio frequency cavities to operate in superconducting magnets. One method to shrink the radii of the cavities is to load them with a dielectric material. The dielectric constant, loss tangent, and dielectric strength are important in determining the most suitable material. Low powered RF measurements of the dielectric constant and loss tangent were taken for multiple purities of alumina and magnesium calcium titanate, as well as cordierite, forsterite, and aluminum nitride. Measurements of alumina were consistent with previously reported results. The results were used to design an insert for a high powered RF test that included sending beam through the cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY050

Export •

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

WEPTY054

Grid Window Tests on an 805-MHz Pillbox Cavity

3393

Y. Torun
Illinois Institute of Technology, Chicago, Illlinois, USA
A. Moretti
Fermilab, Batavia, Illinois, USA

Funding: Supported by the US Department of Energy Office of Science through the Muon Accelerator Program.
Muon ionization cooling channel designs use pillbox shaped RF cavities for improved power efficiency and fine control over phasing of individual cavities. For minimum scattering of the muon beam, the ends should be made out of a small thickness of high radiation length material. Good electrical and thermal conductivity are required to reduce power dissipation and remove the heat efficiently. Thin curved beryllium windows with TiN coating have been used successfully in the past. We have built an alternative window set consisting of grids of tubes and tested these on a pillbox cavity previously used with both thin Be and thick Cu windows. The cavity was operated with a pair of grids as well as a single grid against a flat endplate.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY054

Export •

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

WEPTY055

Installation and Commissioning of the MICE RF Module Prototype

3395

Y. Torun, P.G. Lane
Illinois Institute of Technology, Chicago, Illinois, USA
T.G. Anderson, D.L. Bowring, M. Chung, J.H. Gaynier, M.A. Leonova, A. Moretti, R.J. Pasquinelli, D.W. Peterson, R.P. Schultz
Fermilab, Batavia, Illinois, USA
A.J. DeMello, D. Li, S.P. Virostek
LBNL, Berkeley, California, USA
L. Somaschini
INFN-Pisa, Pisa, Italy

Funding: Supported by the US Department of Energy Office of Science through the Muon Accelerator Program.
A special vacuum vessel prototype was built to house the first production 201 MHz RF cavity for the International Muon Ionization Cooling Experiment (MICE). The resulting prototype RF module has been assembled, instrumented, installed and commissioned at Fermilab's MuCool Test Area and the effort has provided valuable experience for the design of modules that will be used in the cooling channel for the experiment.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY055

Export •

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