eeFACT2016 - Table of Session: TUT1BH (Beam-beam Issues)

Paper	Title	Page
TUT1BH1	Flip-flop Instability in FCC-ee at Low Energies
	D.N. Shatilov BINP SB RAS, Novosibirsk, Russia
	Funding: This work has been supported by Russian Science Foundation (project N14-50-00080). At the energies of FCC-ee beam-beam effects get an extra dimension due to beamstrahlung - radiation in the field of the oncoming bunch. At high energies (175, 120 GeV) it limits the beam lifetime due to possible ingress of particles beyond the energy acceptance. At low energies (80, 45.5 GeV) beamstrahlung may lead to significant growth of the energy spread (and therefore the bunch length). We employed quasi-strong-strong tracking code Lifetrac to study the beam-beam effects in FCC-ee at 45.5 GeV. It was found that the collider performance here is limited by a peculiar flip-flop instability, which is triggered by the bunch lengthening due to beamstrahlung. We discuss how it depends on different parameters: RF voltage, horizontal emittance and beta-function, betatron coupling, asymmetry in the bunch currents. In order to achieve higher luminosity, it is proposed to decrease beta-x at the IP and to increase emittance-x.
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TUT1BH2	Study of Coherent Head-tail Instablility Due to Beam-beam Interaction in Cirular Colliders Based on Crab Waist Scheme	61
	K. Ohmi KEK, Ibaraki, Japan
	FCC-ee is being studied various collision schemes, head-on and large Piwinski angle/ crab waist schemes. We discuss beam-beam limit in the collision schemes using weak-strong and strong-strong models.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT1BH2
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Paper

Title

Page

TUT1BH1

Flip-flop Instability in FCC-ee at Low Energies

D.N. Shatilov
BINP SB RAS, Novosibirsk, Russia

Funding: This work has been supported by Russian Science Foundation (project N14-50-00080).
At the energies of FCC-ee beam-beam effects get an extra dimension due to beamstrahlung - radiation in the field of the oncoming bunch. At high energies (175, 120 GeV) it limits the beam lifetime due to possible ingress of particles beyond the energy acceptance. At low energies (80, 45.5 GeV) beamstrahlung may lead to significant growth of the energy spread (and therefore the bunch length). We employed quasi-strong-strong tracking code Lifetrac to study the beam-beam effects in FCC-ee at 45.5 GeV. It was found that the collider performance here is limited by a peculiar flip-flop instability, which is triggered by the bunch lengthening due to beamstrahlung. We discuss how it depends on different parameters: RF voltage, horizontal emittance and beta-function, betatron coupling, asymmetry in the bunch currents. In order to achieve higher luminosity, it is proposed to decrease beta-x at the IP and to increase emittance-x.

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

TUT1BH2

Study of Coherent Head-tail Instablility Due to Beam-beam Interaction in Cirular Colliders Based on Crab Waist Scheme

61

K. Ohmi
KEK, Ibaraki, Japan

FCC-ee is being studied various collision schemes, head-on and large Piwinski angle/ crab waist schemes. We discuss beam-beam limit in the collision schemes using weak-strong and strong-strong models.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-TUT1BH2

Export •

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