IPAC2019 - List of Authors (Wang, H.)

Paper	Title	Page
MOPRB080	Transient Beam Loading and Mitigation in JLEIC Collider Rings	758
	J. Guo, R.A. Rimmer, H. Wang, S. Wang JLab, Newport News, Virginia, USA J.D. Fox Stanford University, Stanford, California, USA T. Mastoridis CalPoly, San Luis Obispo, California, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, with additional support from U.S. DOE Award Number DE-SC-0019287 The Jefferson Lab Electron-Ion Collider (JLEIC) is an asymmetric high luminosity ring-ring collider proposed as the next major R&D facility for the nuclear physics community. Both of JLEIC’s electron and ion collider rings have high beam current with gaps serving the pur-poses of beam abort, ion clearing, etc. Such a time-varying beam loading in the RF cavities would generate modulation in cavity RF phase/voltage, causing cyclic shift of collision point and potential luminosity loss. We studied a few approaches to mitigate the RF phase modu-lation and IP shift, such as correcting the RF phase/voltage modulation with traditional LLRF feed-back, one-turn feedback (OTFB), or RF feedforward (FF); optimizing the bunch fill pattern to limit the RF phase/voltage modulation to a small fraction of the bunch trains in the collider ring; or matching the RF phase modulation in the two rings. The preliminary re-sults are discussed in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB080
About •	paper received ※ 23 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019
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TUPGW019	Progress of the BESSY VSR Cold String Development and Testing	1434
	H.-W. Glock, V. Dürr, F. Glöckner, J. Knobloch, M. Tannert, A.V. Vélez, D. Wolk, N. Wunderer HZB, Berlin, Germany J. Guo, R.A. Rimmer, H. Wang JLab, Newport News, Virginia, USA
	The so-called VSR (Variable Storage Ring) upgrade of the 3rd gen. light source BESSY II will provide the capability to simultaneously store long (about 20 ps rms length) and short (1 ps or less) bunches in the ring. This will be accomplished by inserting a module with four superconducting cavities, two of them operating at 1.5 GHz as the third harmonic of the 500 MHz driving RF, two at 1.75 GHz. The "cold" string of those four cavities also includes supporting and connecting devices, as there will be: - three intermediate bellows, all shielded against leaking fundamental mode cavity fields, one additionally acting as a collimator for incident synchrotron light; - two tuneable bellows at the module ends; - two warm end groups outside the module, housing toroidal dielectric wake field absorbers, another bellow and a vacuum pump connection. The recent design progress of those components will be reported, including a description of a beam test planned for the central collimating shielded bellow.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW019
About •	paper received ※ 22 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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WEXXPLS1	Magnetron R&D for High Efficiency CW RF Sources of Particle Accelerators	2233
	H. Wang, R.M. Nelson, R.A. Rimmer JLab, Newport News, Virginia, USA B.R.L. Coriton, C.P. Moeller GA, San Diego, California, USA A. Dudas, M.L. Neubauer Muons, Inc, Illinois, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, DOE OS/NP STTR Grant DE-SC0013203 and DOE OS/HEP Accelerator Stewardship award 2019-2021. The scheme of using a high efficiency magnetron to drive a superconducting or normal conducting radio frequency accelerator cavity needs not only injection phase locking but also amplitude modulation to compensate for the cavity’s microphonics, frequency change, variations of cavity voltage and beam current. To be able to do a fast and efficient modulation and to compensate the frequency pushing effect due to the anode current change, the magnetron’s magnetic field has to be trimmed by an external coil. To facilitate this, a low eddy current magnetron body has been designed and built. This paper will present the experimental results of such modulation on a conventional 2.45 GHz magnetron at the R&D test stand. In addition, the progresses on the injection lock test to a new 1497 MHz, 13kW magnetron prototype aimed for the CEBAF klystron replacement with newly built low level RF (LLRF) controller for the amplitude modulation will be reported. Based on these R&D results, a 915MHz, 2×75kW CW industrial heating type magnetron system is being developed to be used for the high efficiency (>80%) RF source to the electron accelerator for industrial applications. H. Wang, et al,THPAL145, proceedings of IPAC 2018. ** M. Neubauer, et al,THPAL042, proceedings of IPAC 2018.
	Slides WEXXPLS1 [8.033 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEXXPLS1
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEPRB099	Status Update of a Harmonic Kicker Development for JLEIC	3047
	G.-T. Park, J. Guo, J. Henry, M. Marchlik, F. Marhauser, R.A. Rimmer, H. Wang, S. Wang JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. An effort to develop the second prototype of the harmonic kicker for the Circulator Cooler Ring (CCR) of the Jefferson Lab Electron-Ion Collider (JLEIC) is under way. After beam dynamics studies and completion of a conceptual RF design of the kicker [1], further progress has been made toward the final mechanical design including the input power coupler (loop) design, tuner ports, multipacting studies. Furthermore, concerning the kicker’s compatibility with beam dynamics, the impact of RF multipole components was investigated and a scheme was developed to cancel out detrimental beam effects. 1. G. Park, et al, The Development of a New Fast Harmonic Kicker for the JLEIC Circulator Cooler Ring, TUPAL068, proceedings of IPAC 2018.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB099
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THXXPLM3	Experimental and Simulation Studies of Cooling of a Bunched Ion Beam in a Storage Ring by a Bunched Electron Beam
	Y. Zhang, S.V. Benson, A. Hutton, K. Jordan, T. Powers, R.A. Rimmer, M.F. Spata, A.V. Sy, H. Wang, S. Wang, H. Zhang JLab, Newport News, Virginia, USA J. Li, X.M. Ma, L.J. Mao, M.T. Tang, J.C. Yang, X.D. Yang, H. Zhao, H.W. Zhao IMP/CAS, Lanzhou, People’s Republic of China
	Cooling of a high energy ion beam is essential for future electron-ion colliders to reach high luminosity. It is critical to demonstrate experimentally cooling by a bunched electron beam and to benchmark the experimental data with simulations. Such experimental and simulation studies were carried out by a collaboration of Jefferson Lab and Institute of Modern Physics (IMP), utilizing a DC cooler at IMP. The thermionic gun of the DC cooler was modified by pulsing its grid voltage to produce cooling electron pulses in a pulse length range of 0.07 - 3.5 µs, with a 250 kHZ repetition frequency. The performed experiments clearly demonstrated cooling of a RF focused ion bunches by this pulsed electron beam. The momentum spread of cooled ion bunch has been reduced from ~2x10^-3 to ~6x10-4 in less than 0.5 second. The simulation results agree with the measurements qualitatively. In this paper, we present a brief overview of the experiments and also show the main experimental and simulation results.
	Slides THXXPLM3 [6.436 MB]
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THPTS090	Injection Locked 1497 MHz Magnetron	4322
	M.L. Neubauer, M.A. Cummings, A. Dudas, R.P. Johnson, S.A. Kahn, G.M. Kazakevich, M. Popovic Muons, Inc, Illinois, USA R.A. Rimmer, H. Wang JLab, Newport News, Virginia, USA
	Muons, In is building an amplitude modulated phase-locked magnetron to replace the klystrons in CEBAF. To do that requires changing the magnetic field at a rate that would induce eddy currents in the standard magnetron. We report on the status of the project to make a stainless steel anode with copper elements to minimize heating while the stainless steel reduces eddy current effects. The construction of the magnetron is two months from completion, while the test stand is ready for delivery of the magnetron
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS090
About •	paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Transient Beam Loading and Mitigation in JLEIC Collider Rings

758

J. Guo, R.A. Rimmer, H. Wang, S. Wang
JLab, Newport News, Virginia, USA
J.D. Fox
Stanford University, Stanford, California, USA
T. Mastoridis
CalPoly, San Luis Obispo, California, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, with additional support from U.S. DOE Award Number DE-SC-0019287
The Jefferson Lab Electron-Ion Collider (JLEIC) is an asymmetric high luminosity ring-ring collider proposed as the next major R&D facility for the nuclear physics community. Both of JLEIC’s electron and ion collider rings have high beam current with gaps serving the pur-poses of beam abort, ion clearing, etc. Such a time-varying beam loading in the RF cavities would generate modulation in cavity RF phase/voltage, causing cyclic shift of collision point and potential luminosity loss. We studied a few approaches to mitigate the RF phase modu-lation and IP shift, such as correcting the RF phase/voltage modulation with traditional LLRF feed-back, one-turn feedback (OTFB), or RF feedforward (FF); optimizing the bunch fill pattern to limit the RF phase/voltage modulation to a small fraction of the bunch trains in the collider ring; or matching the RF phase modulation in the two rings. The preliminary re-sults are discussed in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB080

About •

paper received ※ 23 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019

Export •

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

TUPGW019

Progress of the BESSY VSR Cold String Development and Testing

1434

H.-W. Glock, V. Dürr, F. Glöckner, J. Knobloch, M. Tannert, A.V. Vélez, D. Wolk, N. Wunderer
HZB, Berlin, Germany
J. Guo, R.A. Rimmer, H. Wang
JLab, Newport News, Virginia, USA

The so-called VSR (Variable Storage Ring) upgrade of the 3rd gen. light source BESSY II will provide the capability to simultaneously store long (about 20 ps rms length) and short (1 ps or less) bunches in the ring. This will be accomplished by inserting a module with four superconducting cavities, two of them operating at 1.5 GHz as the third harmonic of the 500 MHz driving RF, two at 1.75 GHz. The "cold" string of those four cavities also includes supporting and connecting devices, as there will be: - three intermediate bellows, all shielded against leaking fundamental mode cavity fields, one additionally acting as a collimator for incident synchrotron light; - two tuneable bellows at the module ends; - two warm end groups outside the module, housing toroidal dielectric wake field absorbers, another bellow and a vacuum pump connection. The recent design progress of those components will be reported, including a description of a beam test planned for the central collimating shielded bellow.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW019

About •

paper received ※ 22 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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

WEXXPLS1

Magnetron R&D for High Efficiency CW RF Sources of Particle Accelerators

2233

H. Wang, R.M. Nelson, R.A. Rimmer
JLab, Newport News, Virginia, USA
B.R.L. Coriton, C.P. Moeller
GA, San Diego, California, USA
A. Dudas, M.L. Neubauer
Muons, Inc, Illinois, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, DOE OS/NP STTR Grant DE-SC0013203 and DOE OS/HEP Accelerator Stewardship award 2019-2021.
The scheme of using a high efficiency magnetron to drive a superconducting or normal conducting radio frequency accelerator cavity needs not only injection phase locking but also amplitude modulation to compensate for the cavity’s microphonics, frequency change, variations of cavity voltage and beam current. To be able to do a fast and efficient modulation and to compensate the frequency pushing effect due to the anode current change, the magnetron’s magnetic field has to be trimmed by an external coil*. To facilitate this, a low eddy current magnetron body has been designed and built**. This paper will present the experimental results of such modulation on a conventional 2.45 GHz magnetron at the R&D test stand. In addition, the progresses on the injection lock test to a new 1497 MHz, 13kW magnetron prototype aimed for the CEBAF klystron replacement with newly built low level RF (LLRF) controller for the amplitude modulation will be reported. Based on these R&D results, a 915MHz, 2×75kW CW industrial heating type magnetron system is being developed to be used for the high efficiency (>80%) RF source to the electron accelerator for industrial applications.
* H. Wang, et al,THPAL145, proceedings of IPAC 2018.
** M. Neubauer, et al,THPAL042, proceedings of IPAC 2018.

Slides WEXXPLS1 [8.033 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEXXPLS1

About •

paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

Export •

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

WEPRB099

Status Update of a Harmonic Kicker Development for JLEIC

3047

G.-T. Park, J. Guo, J. Henry, M. Marchlik, F. Marhauser, R.A. Rimmer, H. Wang, S. Wang
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
An effort to develop the second prototype of the harmonic kicker for the Circulator Cooler Ring (CCR) of the Jefferson Lab Electron-Ion Collider (JLEIC) is under way. After beam dynamics studies and completion of a conceptual RF design of the kicker [1], further progress has been made toward the final mechanical design including the input power coupler (loop) design, tuner ports, multipacting studies. Furthermore, concerning the kicker’s compatibility with beam dynamics, the impact of RF multipole components was investigated and a scheme was developed to cancel out detrimental beam effects.
1. G. Park, et al, The Development of a New Fast Harmonic Kicker for the JLEIC Circulator Cooler Ring, TUPAL068, proceedings of IPAC 2018.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB099

About •

paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

Export •

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

THXXPLM3

Experimental and Simulation Studies of Cooling of a Bunched Ion Beam in a Storage Ring by a Bunched Electron Beam

Y. Zhang, S.V. Benson, A. Hutton, K. Jordan, T. Powers, R.A. Rimmer, M.F. Spata, A.V. Sy, H. Wang, S. Wang, H. Zhang
JLab, Newport News, Virginia, USA
J. Li, X.M. Ma, L.J. Mao, M.T. Tang, J.C. Yang, X.D. Yang, H. Zhao, H.W. Zhao
IMP/CAS, Lanzhou, People’s Republic of China

Cooling of a high energy ion beam is essential for future electron-ion colliders to reach high luminosity. It is critical to demonstrate experimentally cooling by a bunched electron beam and to benchmark the experimental data with simulations. Such experimental and simulation studies were carried out by a collaboration of Jefferson Lab and Institute of Modern Physics (IMP), utilizing a DC cooler at IMP. The thermionic gun of the DC cooler was modified by pulsing its grid voltage to produce cooling electron pulses in a pulse length range of 0.07 - 3.5 µs, with a 250 kHZ repetition frequency. The performed experiments clearly demonstrated cooling of a RF focused ion bunches by this pulsed electron beam. The momentum spread of cooled ion bunch has been reduced from ~2x10^-3 to ~6x10-4 in less than 0.5 second. The simulation results agree with the measurements qualitatively. In this paper, we present a brief overview of the experiments and also show the main experimental and simulation results.

Slides THXXPLM3 [6.436 MB]

Export •

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

THPTS090

Injection Locked 1497 MHz Magnetron

4322

M.L. Neubauer, M.A. Cummings, A. Dudas, R.P. Johnson, S.A. Kahn, G.M. Kazakevich, M. Popovic
Muons, Inc, Illinois, USA
R.A. Rimmer, H. Wang
JLab, Newport News, Virginia, USA

Muons, In is building an amplitude modulated phase-locked magnetron to replace the klystrons in CEBAF. To do that requires changing the magnetic field at a rate that would induce eddy currents in the standard magnetron. We report on the status of the project to make a stainless steel anode with copper elements to minimize heating while the stainless steel reduces eddy current effects. The construction of the magnetron is two months from completion, while the test stand is ready for delivery of the magnetron

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS090

About •

paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

Export •

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