IPAC2018 - List of Authors (Wang, S.)

Paper	Title	Page
MOPMK017	Transient Beam Loading Due to the Bunch Train Gap and Its Compensation Experiments at BEPC-II and ALS	390
	H. Wang, R.A. Rimmer, S. Wang JLab, Newport News, Virginia, USA J.P. Dai, Q. Qin, J. Xing, J.H. Yue, Y. Zhang IHEP, Beijing, People's Republic of China D. Teytelman Dimtel, San Jose, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Non-uniform bunch fill patterns in storage rings, driven by the need to provide gaps for beam aborting and ion clearing cause a large beam loading change in the RF cavities. The induced turn-periodic transient in the cavity voltage modulates longitudinal beam properties along the train, such as synchronous position and bunch length. In the EIC design, due to the asymmetric bunch train structure between the electron and the ion beam, such modulation results in shifting collision point and leads to reduced luminosity. We have carried out the beam based experiments at BEPC-II and ALS using bunch-by-bunch diagnostic capabilities of the coupled-bunch feedback systems to study this transient effect. A modulated bunch filling pattern with higher charge density around the gap has been demonstrated to be effective in partially compensating this transient modulation. Details of the experimental setups and the data analysis will be presented to this conference.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK017
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL068	The Development of a Nw Fast Harmonic Kicker for the JLEIC Circulator Cooling Ring	1171
	G.-T. Park, F. Fors, J. Guo, 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. After the first half-scale, 5 harmonic kicker cavity prototyping * for the JLEIC's CCR/ERL electron cooler and the beam dynamic simulation study of the 10-turn CCR *. The optimized circulation cooling turns has been changed to 11 and only 5 odd-harmonic modes from 86.6 MHz to 779.4 MHz plus a DC bias are needed for the harmonic RF kicker system. The new cavity design including the electromagnetic and thermal cooling optimization and its 11 turns beam bunch tracking simulation with the new numerology of RF deflecting voltages will be presented. Further design specifications for its RF harmonic drive and the broadband RF window, coupler and circulator component will be given for handling 5 kW of total RF power. Y, Huang, H. Wang et al., Physical Review Accelerators and Beams 19, 122001 (2016). ** Y. Huang, H. Wang et al., Physical Review Accelerators and Beams 19, 084201 (2016).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL068
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL069	Experimental Demonstration of Ion Beam Cooling with Pulsed Electron Beam	1174
	Y. Zhang, A. Hutton, K. Jordan, T. Powers, R.A. Rimmer, M. F. Spata, 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
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Cooling ion beams at high energy is presently considered for several ion colliders, in order to achieve high luminosities by enabling a significant reduction of emittance of hadron beams. Electron beam at cooling channel in a few to tens MeV can be accelerated by a RF/SRF linac, and thus using bunched electrons to cool bunched ions. To study such cooling process, the DC electron gun of EC35 cooler at the storage ring CSRm, IMP was modified by pulsing the grid voltage. A 0.07-3.5 micro-second pulse length with a repetition frequency of less than 250 kHz and synchronized with the ion revolution frequency was obtained. The first experimental demonstration of cooling of a coasting and bunched ion beam by a pulsed electron beam was carried out. Data analysis indicates the bunch length shrinkage and the momentum spread reduction of bunched 12C+6 ion beam as evidence of cooling. A longitudinal grouping effect of the coasting ion beam by the electron pulses has also been observed. In this paper, we will present experimental results and comparison to the simulation modelling, particularly on the bunched electron cooling data after carefully analyzing the beam diagnostic signals. L.J. Mao et al., Experimental Demonstration of Electron Cooling with Bunched Electron Beam, TUP15, Proceedings of COOL2017, Bonn, Germany
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL069
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAK122	Longitudinal Coupled Bunch Instability in JLEIC	3530
	R. Li, J. Guo, F. Marhauser, S. Wang JLab, Newport News, Virginia, USA
	Funding: This work is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The luminosity performance of the JLEIC design is achieved by using a high bunch repetition rate (476MHz) with moderate bunch charges, similar to the strategy employed in modern lepton colliders. Such a bunch configuration will make single bunch instabilities less probable, yet makes the machine more prone to the onset of longitudinal and transverse coupled bunch instabilities. Consequently, this will set higher demands on the bunch-by-bunch feedback systems to mitigate the multi-bunch instabilities. In this paper we present our detailed analysis of the growth rate of the coupled bunch instabilities for beams in both the electron and ion rings in JLEIC at the collision scenario. The implication of the growth rate on the feedback system will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK122
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL144	952.6 MHz SRF Cavity Development for JLEIC	3982
	R.A. Rimmer, W.A. Clemens, F. Fors, J. Guo, F.E. Hannon, J. Henry, F. Marhauser, L. Turlington, 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 JLab is developing new SRF cavity designs at 952.6 MHz for the proposed Jefferson Lab Electron-Ion Collider (JLEIC). New cavities will be required for the ion ring, cooler ERL and booster and eventually for an upgrade of the electron ring to allow the highest possible bunch collision rate. The challenges include the need for high fundamental mode power couplers and strong HOM damping, with high HOM power capability. Initial focus is on the cooler ERL 5-cell cavity as this is a critical component for the strong, high energy, bunched-beam cooling concept. 1-cell and 5-cell Nb prototype cavities have been designed and fabricated. Details concerning the cavity fabrication and test results will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL144
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Transient Beam Loading Due to the Bunch Train Gap and Its Compensation Experiments at BEPC-II and ALS

390

H. Wang, R.A. Rimmer, S. Wang
JLab, Newport News, Virginia, USA
J.P. Dai, Q. Qin, J. Xing, J.H. Yue, Y. Zhang
IHEP, Beijing, People's Republic of China
D. Teytelman
Dimtel, San Jose, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Non-uniform bunch fill patterns in storage rings, driven by the need to provide gaps for beam aborting and ion clearing cause a large beam loading change in the RF cavities. The induced turn-periodic transient in the cavity voltage modulates longitudinal beam properties along the train, such as synchronous position and bunch length. In the EIC design, due to the asymmetric bunch train structure between the electron and the ion beam, such modulation results in shifting collision point and leads to reduced luminosity. We have carried out the beam based experiments at BEPC-II and ALS using bunch-by-bunch diagnostic capabilities of the coupled-bunch feedback systems to study this transient effect. A modulated bunch filling pattern with higher charge density around the gap has been demonstrated to be effective in partially compensating this transient modulation. Details of the experimental setups and the data analysis will be presented to this conference.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK017

Export •

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

TUPAL068

The Development of a Nw Fast Harmonic Kicker for the JLEIC Circulator Cooling Ring

1171

G.-T. Park, F. Fors, J. Guo, 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.
After the first half-scale, 5 harmonic kicker cavity prototyping * for the JLEIC's CCR/ERL electron cooler and the beam dynamic simulation study of the 10-turn CCR **. The optimized circulation cooling turns has been changed to 11 and only 5 odd-harmonic modes from 86.6 MHz to 779.4 MHz plus a DC bias are needed for the harmonic RF kicker system. The new cavity design including the electromagnetic and thermal cooling optimization and its 11 turns beam bunch tracking simulation with the new numerology of RF deflecting voltages will be presented. Further design specifications for its RF harmonic drive and the broadband RF window, coupler and circulator component will be given for handling 5 kW of total RF power.
* Y, Huang, H. Wang et al., Physical Review Accelerators and Beams 19, 122001 (2016).
** Y. Huang, H. Wang et al., Physical Review Accelerators and Beams 19, 084201 (2016).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL068

Export •

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

TUPAL069

Experimental Demonstration of Ion Beam Cooling with Pulsed Electron Beam

1174

Y. Zhang, A. Hutton, K. Jordan, T. Powers, R.A. Rimmer, M. F. Spata, 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

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Cooling ion beams at high energy is presently considered for several ion colliders, in order to achieve high luminosities by enabling a significant reduction of emittance of hadron beams. Electron beam at cooling channel in a few to tens MeV can be accelerated by a RF/SRF linac, and thus using bunched electrons to cool bunched ions. To study such cooling process, the DC electron gun of EC35 cooler at the storage ring CSRm, IMP was modified by pulsing the grid voltage. A 0.07-3.5 micro-second pulse length with a repetition frequency of less than 250 kHz and synchronized with the ion revolution frequency was obtained. The first experimental demonstration of cooling of a coasting and bunched ion beam by a pulsed electron beam was carried out. Data analysis indicates the bunch length shrinkage and the momentum spread reduction of bunched 12C+6 ion beam as evidence of cooling. A longitudinal grouping effect of the coasting ion beam by the electron pulses has also been observed*. In this paper, we will present experimental results and comparison to the simulation modelling, particularly on the bunched electron cooling data after carefully analyzing the beam diagnostic signals.
* L.J. Mao et al., Experimental Demonstration of Electron Cooling with Bunched Electron Beam, TUP15, Proceedings of COOL2017, Bonn, Germany

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL069

Export •

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

THPAK122

Longitudinal Coupled Bunch Instability in JLEIC

3530

R. Li, J. Guo, F. Marhauser, S. Wang
JLab, Newport News, Virginia, USA

Funding: This work is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The luminosity performance of the JLEIC design is achieved by using a high bunch repetition rate (476MHz) with moderate bunch charges, similar to the strategy employed in modern lepton colliders. Such a bunch configuration will make single bunch instabilities less probable, yet makes the machine more prone to the onset of longitudinal and transverse coupled bunch instabilities. Consequently, this will set higher demands on the bunch-by-bunch feedback systems to mitigate the multi-bunch instabilities. In this paper we present our detailed analysis of the growth rate of the coupled bunch instabilities for beams in both the electron and ion rings in JLEIC at the collision scenario. The implication of the growth rate on the feedback system will be discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK122

Export •

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

THPAL144

952.6 MHz SRF Cavity Development for JLEIC

3982

R.A. Rimmer, W.A. Clemens, F. Fors, J. Guo, F.E. Hannon, J. Henry, F. Marhauser, L. Turlington, 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
JLab is developing new SRF cavity designs at 952.6 MHz for the proposed Jefferson Lab Electron-Ion Collider (JLEIC). New cavities will be required for the ion ring, cooler ERL and booster and eventually for an upgrade of the electron ring to allow the highest possible bunch collision rate. The challenges include the need for high fundamental mode power couplers and strong HOM damping, with high HOM power capability. Initial focus is on the cooler ERL 5-cell cavity as this is a critical component for the strong, high energy, bunched-beam cooling concept. 1-cell and 5-cell Nb prototype cavities have been designed and fabricated. Details concerning the cavity fabrication and test results will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL144

Export •

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