IPAC2014 - List of Authors (Billing, M.G.)

Paper	Title	Page
MOPRO113	Beam-based HOM Measurements in Cornell's ERL Main Linac Cavity	359
	D.L. Hall, A.C. Bartnik, M.G. Billing, D. Gonnella, G.H. Hoffstaetter, M. Liepe, C.E. Mayes Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	A search for HOMs in Cornell’s ERL main linac cavity installed in a Horizontal Test Cryomodule (HTC) has been carried out using a bunch charge modulation method, as part of the effort towards building an Energy Recovery Linac (ERL). The beam-based HOM measurements offer the significant advantage of being able to detect trapped modes invisible to both the RF pickup probes and HOM damping loads, and allow for measuring the R/Q of the modes. For each HOM detected during the search, measurements were taken to determine its nature (monopole, dipole, etc.), frequency, loaded quality factor and shunt impedance. A selection of the most notable modes found is presented, compared to 3D HOM simulations, and their potential impact on the BBU current of the future Cornell ERL is discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO113
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TUPRI034	Numerical Modeling for CesrTA Measurements of Electron Cloud Buildup in a Quadrupole Magnet	1632
	J.A. Crittenden, M.G. Billing, W. Hartung, C. Shill, J.P. Sikora, K.G. Sonnad Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work supported by the U.S. National Science Foundation contracts PHY-0734867, PHY-1002467, and the U.S. Department of Energy contract DE-FC02-08ER41538 We describe a numerical model for measurements of the formation of long-lived electron clouds in a quadrupole magnet in the CESR storage ring. The shielded stripline detector measures the electron flux incident on the vacuum chamber wall directly in front of one of the poles of the magnet. The model includes photo-electron production by synchrotron radiation, electrostatic forces from the bunched positron beam and the cloud, macroparticle tracking in the field of the quadrupole, secondary electron emission from the 9.5-cm-diameter cylindrical stainless steel beam-pipe and an analytic calculation of the transmission function of the holes in the vacuum chamber which allow cloud electrons to reach the stripline collector. These modeling studies provide a quantitative understanding of the trapping mechanism which results in cloud electrons surviving the 2.3-microsecond time interval prior to the return of a train of positron bunches. These studies have been performed in the context of the CESR Test Accelerator program, which aims to quantify and mitigate performance limitations on future low-emittance storage and damping rings.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI034
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TUPRI067	Recent Results for the Dependence of Beam Instabilities caused by Electron Clouds at CesrTA due to Variations in Bunch Spacing and Chromaticity	1721
	M.G. Billing, K.R. Butler, G. Dugan, M.J. Forster, G. Ramirez, N.T. Rider, K.G. Sonnad, H.A. Williams Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA J.W. Flanagan KEK, Ibaraki, Japan R. Holtzapple, K.E. McArdle, M.I. Miller, M.M. Totten CalPoly, San Luis Obispo, California, USA
	Funding: Work supported by DOE Award DE-FC02-08ER41538, NSF Award PHY-0734867, PHY-1068662 and the Lepton Collider R&D, Coop Agreement: NSF Award PHY-1002467 At the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) experiments have been studying the interaction of the electron cloud (EC) with 2.1 GeV stored electron and positron beams. These experiments are intended to characterize the dependence of beam–EC interactions on various beam parameters, such as bunch spacing and vertical chromaticity. Most experiments were performed with 30 or 45-bunch trains, at a fixed current of 0.75 mA/bunch. Earlier experiments with positrons had varied the bunch spacing between 4 and 56 ns at three different vertical chromaticity settings. More recent measurements have included electron-bunch trains to contrast the build up of EC between electron and positron beams. The dynamics of the stored beam was quantified using: a gated Beam Position Monitor (BPM) and spectrum analyzer to measure the frequency spectrum of bunches in the trains; an x-ray beam size monitor to record the bunch-by-bunch, turn-by-turn vertical size of each bunch within the trains. We report on recent ob-servations from these experiments and additional studies, using witness bunches trailing 30 or 45-bunch positron trains, which were used for the generation of the ECs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI067
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THPME189	Simulation Studies of Diffraction Radiation	3722
	T. Aumeyr, R. Ainsworth, P. Karataev Royal Holloway, University of London, Surrey, United Kingdom M.G. Billing Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA L.M. Bobb, B. Bolzon, T. Lefèvre, S. Mazzoni CERN, Geneva, Switzerland
	Transition Radiation (TR) and Diffraction Radiation (DR) are produced when a relativistic charged particle moves through a medium or in the vicinity of a medium respectively. The target atoms are polarised by the electric field of the charged particle, which then oscillate thus emitting radiation with a very broad spectrum. The spatial-spectral properties of TR/DR are sensitive to various electron beam parameters. Several projects aim to measure the transverse (vertical) beam size using TR or DR. This paper reports on recent studies using Zemax, presenting studies on finite beam sizes and the orientation of the beam ellipse.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME189
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Paper

Title

Page

Beam-based HOM Measurements in Cornell's ERL Main Linac Cavity

359

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

A search for HOMs in Cornell’s ERL main linac cavity installed in a Horizontal Test Cryomodule (HTC) has been carried out using a bunch charge modulation method, as part of the effort towards building an Energy Recovery Linac (ERL). The beam-based HOM measurements offer the significant advantage of being able to detect trapped modes invisible to both the RF pickup probes and HOM damping loads, and allow for measuring the R/Q of the modes. For each HOM detected during the search, measurements were taken to determine its nature (monopole, dipole, etc.), frequency, loaded quality factor and shunt impedance. A selection of the most notable modes found is presented, compared to 3D HOM simulations, and their potential impact on the BBU current of the future Cornell ERL is discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO113

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TUPRI034

Numerical Modeling for CesrTA Measurements of Electron Cloud Buildup in a Quadrupole Magnet

1632

J.A. Crittenden, M.G. Billing, W. Hartung, C. Shill, J.P. Sikora, K.G. Sonnad
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by the U.S. National Science Foundation contracts PHY-0734867, PHY-1002467, and the U.S. Department of Energy contract DE-FC02-08ER41538
We describe a numerical model for measurements of the formation of long-lived electron clouds in a quadrupole magnet in the CESR storage ring. The shielded stripline detector measures the electron flux incident on the vacuum chamber wall directly in front of one of the poles of the magnet. The model includes photo-electron production by synchrotron radiation, electrostatic forces from the bunched positron beam and the cloud, macroparticle tracking in the field of the quadrupole, secondary electron emission from the 9.5-cm-diameter cylindrical stainless steel beam-pipe and an analytic calculation of the transmission function of the holes in the vacuum chamber which allow cloud electrons to reach the stripline collector. These modeling studies provide a quantitative understanding of the trapping mechanism which results in cloud electrons surviving the 2.3-microsecond time interval prior to the return of a train of positron bunches. These studies have been performed in the context of the CESR Test Accelerator program, which aims to quantify and mitigate performance limitations on future low-emittance storage and damping rings.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI034

Export •

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

TUPRI067

Recent Results for the Dependence of Beam Instabilities caused by Electron Clouds at CesrTA due to Variations in Bunch Spacing and Chromaticity

1721

M.G. Billing, K.R. Butler, G. Dugan, M.J. Forster, G. Ramirez, N.T. Rider, K.G. Sonnad, H.A. Williams
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J.W. Flanagan
KEK, Ibaraki, Japan
R. Holtzapple, K.E. McArdle, M.I. Miller, M.M. Totten
CalPoly, San Luis Obispo, California, USA

Funding: Work supported by DOE Award DE-FC02-08ER41538, NSF Award PHY-0734867, PHY-1068662 and the Lepton Collider R&D, Coop Agreement: NSF Award PHY-1002467
At the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) experiments have been studying the interaction of the electron cloud (EC) with 2.1 GeV stored electron and positron beams. These experiments are intended to characterize the dependence of beam–EC interactions on various beam parameters, such as bunch spacing and vertical chromaticity. Most experiments were performed with 30 or 45-bunch trains, at a fixed current of 0.75 mA/bunch. Earlier experiments with positrons had varied the bunch spacing between 4 and 56 ns at three different vertical chromaticity settings. More recent measurements have included electron-bunch trains to contrast the build up of EC between electron and positron beams. The dynamics of the stored beam was quantified using: a gated Beam Position Monitor (BPM) and spectrum analyzer to measure the frequency spectrum of bunches in the trains; an x-ray beam size monitor to record the bunch-by-bunch, turn-by-turn vertical size of each bunch within the trains. We report on recent ob-servations from these experiments and additional studies, using witness bunches trailing 30 or 45-bunch positron trains, which were used for the generation of the ECs.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI067

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

THPME189

Simulation Studies of Diffraction Radiation

3722

T. Aumeyr, R. Ainsworth, P. Karataev
Royal Holloway, University of London, Surrey, United Kingdom
M.G. Billing
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
L.M. Bobb, B. Bolzon, T. Lefèvre, S. Mazzoni
CERN, Geneva, Switzerland

Transition Radiation (TR) and Diffraction Radiation (DR) are produced when a relativistic charged particle moves through a medium or in the vicinity of a medium respectively. The target atoms are polarised by the electric field of the charged particle, which then oscillate thus emitting radiation with a very broad spectrum. The spatial-spectral properties of TR/DR are sensitive to various electron beam parameters. Several projects aim to measure the transverse (vertical) beam size using TR or DR. This paper reports on recent studies using Zemax, presenting studies on finite beam sizes and the orientation of the beam ellipse.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME189

Export •

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