HB2018 - List of Authors (Baudrenghien, P.)

Paper	Title	Page
WEP2PO003	Beam Loading and Longitudinal Stability Evaluation for the FCC-ee Rings	266
	I. Karpov, P. Baudrenghien CERN, Geneva, Switzerland
	In high-current accelerators, interaction of the beam with fundamental impedance of the accelerating cavities can limit machine performance. It can result in a significant variation of bunch-by-bunch parameters (bunch length, synchronous phase, etc.) and lead to longitudinal coupled-bunch instability. In this work, these limitations are analysed together with possible cures for the high-current option (Z machine) of the future circular electron-positron collider (FCC-ee). The time-domain calculations of steady-state beam loading are presented and compared with frequency-domain analysis.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-WEP2PO003
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THP2WC02	LLRF Studies for HL-LHC Crab Cavities	440
	P. Baudrenghien CERN, Geneva, Switzerland T. Mastoridis CalPoly, San Luis Obispo, California, USA
	The HL-LHC upgrade includes sixteen Crab Cavities (CC) to be installed on both sides of the high luminosity experiments, ATLAS and CMS. Two issues have been highlighted for the Low Level RF: transverse emittance growth (and associated luminosity drop) caused by CC RF noise, and large collimator losses following a CC trip. A prototype cryomodule with two CCs has been installed in the SPS, and tests have started in May 2018 with beam. This paper briefly reports on preliminary results from the SPS tests. It then presents emittance growth calculations from cavity field phase and amplitude noise, deduces the maximum RF noise compatible with the specifications and presents a possible cure consisting of a feedback on CC phase and amplitude. To reduce the losses following a CC trip we propose to implement transverse tail cleaning via the injection of CC noise with an optimized spectrum, which selectively excites the particles of large transverse oscillation amplitudes.
	Slides THP2WC02 [1.943 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THP2WC02
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Beam Loading and Longitudinal Stability Evaluation for the FCC-ee Rings

266

I. Karpov, P. Baudrenghien
CERN, Geneva, Switzerland

In high-current accelerators, interaction of the beam with fundamental impedance of the accelerating cavities can limit machine performance. It can result in a significant variation of bunch-by-bunch parameters (bunch length, synchronous phase, etc.) and lead to longitudinal coupled-bunch instability. In this work, these limitations are analysed together with possible cures for the high-current option (Z machine) of the future circular electron-positron collider (FCC-ee). The time-domain calculations of steady-state beam loading are presented and compared with frequency-domain analysis.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-WEP2PO003

Export •

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

THP2WC02

LLRF Studies for HL-LHC Crab Cavities

440

P. Baudrenghien
CERN, Geneva, Switzerland
T. Mastoridis
CalPoly, San Luis Obispo, California, USA

The HL-LHC upgrade includes sixteen Crab Cavities (CC) to be installed on both sides of the high luminosity experiments, ATLAS and CMS. Two issues have been highlighted for the Low Level RF: transverse emittance growth (and associated luminosity drop) caused by CC RF noise, and large collimator losses following a CC trip. A prototype cryomodule with two CCs has been installed in the SPS, and tests have started in May 2018 with beam. This paper briefly reports on preliminary results from the SPS tests. It then presents emittance growth calculations from cavity field phase and amplitude noise, deduces the maximum RF noise compatible with the specifications and presents a possible cure consisting of a feedback on CC phase and amplitude. To reduce the losses following a CC trip we propose to implement transverse tail cleaning via the injection of CC noise with an optimized spectrum, which selectively excites the particles of large transverse oscillation amplitudes.

Slides THP2WC02 [1.943 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THP2WC02

Export •

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