eeFACT2022 - List of Authors (Wang, N.)

Paper	Title	Page
WEXAT0104	Beam-beam Simulations including Coupling Impedance
	Y. Zhang, N. Wang IHEP, Beijing, People’s Republic of China M. Migliorati Sapienza University of Rome, Rome, Italy K. Ohmi, D. Zhou KEK, Ibaraki, Japan M. Zobov LNF-INFN, Frascati, Italy
	The design performance of future e⁺e⁻ ring colliders has been pushed to new extreme based on the crab-waist scheme. The new found coherent head-tail instability (X-Z instability) may induce the horizontal beam size blowup and reduce the machine performance. The longitudinal coupling impedance would distort the phase space: lengthen the bunch and bring incoherent synchrotron tune spread. The simulation study has found the clear influence of longitudinal impedance on the X-Z instability in both CEPC and FCCee. With the evolvement of future machine design process, the transverse impedance has also been included. The results show that a vertical beam-beam TMCI-like instability may be induced when the impedance is considered. It is first found in e⁺e⁻ colliders. Some similar study at SuperKEKB will also be presented. It could be expected or concluded that different effect would couple and determine the final performance together in present and future high performance crab-waist colliders. Separate effect study seems not enough to evaluate and predict the machine performance/stability.
	Slides WEXAT0104 [3.976 MB]
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WEYAT0101	Collective Effects Studies for CEPC	141
	N. Wang, C.T. Lin, Y.D. Liu, S.K. Tian, H.S. Xu, Y. Zhang IHEP, Beijing, People’s Republic of China
	The impedance model of the CEPC storage ring is updated according to the development of the vacuum components based on the circular beam pipe. With the impedance model, the single bunch and coupled bunch instabilities for different operation scenarios are investigated. Particularly, the key instability issues driven by the beam coupling impedance in the Z operation mode are discussed. The influence of the longitudinal impedance on the transverse mode coupling instability is analyzed both numerically and analytically. In addition, trapped ions can induce bunch centroid oscillation and emittance growth. The possibility of ion trapping and fast beam ion instability in the CEPC storage ring are also investigated.
	Slides WEYAT0101 [2.856 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-eeFACT2022-WEYAT0101
About •	Received ※ 30 November 2022 — Revised ※ 03 February 2023 — Accepted ※ 08 February 2023 — Issue date ※ 09 February 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

WEXAT0104

Beam-beam Simulations including Coupling Impedance

Y. Zhang, N. Wang
IHEP, Beijing, People’s Republic of China
M. Migliorati
Sapienza University of Rome, Rome, Italy
K. Ohmi, D. Zhou
KEK, Ibaraki, Japan
M. Zobov
LNF-INFN, Frascati, Italy

The design performance of future e⁺e⁻ ring colliders has been pushed to new extreme based on the crab-waist scheme. The new found coherent head-tail instability (X-Z instability) may induce the horizontal beam size blowup and reduce the machine performance. The longitudinal coupling impedance would distort the phase space: lengthen the bunch and bring incoherent synchrotron tune spread. The simulation study has found the clear influence of longitudinal impedance on the X-Z instability in both CEPC and FCCee. With the evolvement of future machine design process, the transverse impedance has also been included. The results show that a vertical beam-beam TMCI-like instability may be induced when the impedance is considered. It is first found in e⁺e⁻ colliders. Some similar study at SuperKEKB will also be presented. It could be expected or concluded that different effect would couple and determine the final performance together in present and future high performance crab-waist colliders. Separate effect study seems not enough to evaluate and predict the machine performance/stability.

Slides WEXAT0104 [3.976 MB]

Cite •

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

WEYAT0101

Collective Effects Studies for CEPC

141

N. Wang, C.T. Lin, Y.D. Liu, S.K. Tian, H.S. Xu, Y. Zhang
IHEP, Beijing, People’s Republic of China

The impedance model of the CEPC storage ring is updated according to the development of the vacuum components based on the circular beam pipe. With the impedance model, the single bunch and coupled bunch instabilities for different operation scenarios are investigated. Particularly, the key instability issues driven by the beam coupling impedance in the Z operation mode are discussed. The influence of the longitudinal impedance on the transverse mode coupling instability is analyzed both numerically and analytically. In addition, trapped ions can induce bunch centroid oscillation and emittance growth. The possibility of ion trapping and fast beam ion instability in the CEPC storage ring are also investigated.

Slides WEYAT0101 [2.856 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-eeFACT2022-WEYAT0101

About •

Received ※ 30 November 2022 — Revised ※ 03 February 2023 — Accepted ※ 08 February 2023 — Issue date ※ 09 February 2023

Cite •

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