IPAC2019 - List of Authors (Vollinger, C.)

Paper	Title	Page
MOPGW076	Verification by RF Measurements of New HOM Mitigation Scheme Developed for Future SPS 33-Cell Accelerating Structures	274
	P. Kramer, A. Farricker, C. Vollinger CERN, Geneva, Switzerland
	Longitudinal higher-order modes (HOMs) at a frequency of around 630 MHz in the 200 MHz travelling wave RF structures currently limit the beam intensities in the CERN SPS to less than that required by the High Luminosity (HL-) LHC. In the framework of the LHC Injectors Upgrade (LIU) project, the performance of the already existing HOM damping scheme for these standing wave modes must be improved. This involves improving the existing HOM-couplers as well as the possible use of a new mitigation technique via the insertion of resonant posts in some cells of the multi-cell structures. The development of the new damping scheme has been performed using theoretical analysis of the cavity-coupler interaction in conjunction with full-wave electromagnetic (EM) field simulations. This contribution will show the verification of the improved HOM damping performance by measurements on a single section with 11 cells and on the future 33-cell structures. The parasitic impact of the damping scheme on the travelling wave fundamental passband (FPB) will also be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW076
About •	paper received ※ 11 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)

MOPGW077	Impedance Reduction in the CERN SPS Through Element Layout Optimisation	277
	A. Farricker, C. Vollinger CERN, Geneva, Switzerland
	The CERN accelerator complex is currently in its long shutdown while the LHC Injector Upgrade is being carried out. The upgrade of the SPS includes but is not limited to: the relocation of the beam dumping system, upgrade of the RF system, replacement of the electrostatic septa and impedance reduction. These major upgrades present an opportunity to perform additional impedance reduction in areas not normally modified due to the large amount of work being performed across the accelerator complex. In this paper, we look at the impedance minimization in the sections near the large aperture quadrupoles of the extraction regions in the CERN SPS. By optimizing the locations of existing equipment and the introduction of a new, more impedance optimised type of bellows, significant reductions in the beam-coupling impedance can be achieved.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW077
About •	paper received ※ 08 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)

WEYPLS1	Building the Impedance Model of a Real Machine	2249
	B. Salvant, D. Amorim, S.A. Antipov, S. Arsenyev, M.S. Beck, N. Biancacci, O.S. Brüning, J.V. Campelo, E. Carideo, F. Caspers, A. Farricker, A. Grudiev, T. Kaltenbacher, E. Koukovini-Platia, P. Kramer, A. Lasheen, M. Migliorati, N. Mounet, E. Métral, N. Nasr Esfahani, S. Persichelli, B.K. Popovic, T.L. Rijoff, G. Rumolo, E.N. Shaposhnikova, V.G. Vaccaro, C. Vollinger, N. Wang, C. Zannini, B. Zotter CERN, Meyrin, Switzerland D. Amorim Grenoble-INP Phelma, Grenoble, France T. Dalascu EPFL, Lausanne, Switzerland M. Migliorati Sapienza University of Rome, Rome, Italy R. Nagaoka SOLEIL, Gif-sur-Yvette, France V.V. Smaluk BNL, Upton, Long Island, New York, USA B. Spataro INFN/LNF, Frascati, Italy N. Wang IHEP, Beijing, People’s Republic of China S.M. White ESRF, Grenoble, France
	A reliable impedance model of a particle accelerator can be built by combining the beam coupling impedances of all the components. This is a necessary step to be able to evaluate the machine performance limitations, identify the main contributors in case an impedance reduction is required, and study the interaction with other mechanisms such as optics nonlinearities, transverse damper, noise, space charge, electron cloud, beam-beam (in a collider). The main phases to create a realistic impedance model, and verify it experimentally, will be reviewed, highlighting the main challenges. Some examples will be presented revealing the levels of precision of machine impedance models that have been achieved.
	Slides WEYPLS1 [5.648 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYPLS1
About •	paper received ※ 10 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)

Paper

Title

Page

Verification by RF Measurements of New HOM Mitigation Scheme Developed for Future SPS 33-Cell Accelerating Structures

274

P. Kramer, A. Farricker, C. Vollinger
CERN, Geneva, Switzerland

Longitudinal higher-order modes (HOMs) at a frequency of around 630 MHz in the 200 MHz travelling wave RF structures currently limit the beam intensities in the CERN SPS to less than that required by the High Luminosity (HL-) LHC. In the framework of the LHC Injectors Upgrade (LIU) project, the performance of the already existing HOM damping scheme for these standing wave modes must be improved. This involves improving the existing HOM-couplers as well as the possible use of a new mitigation technique via the insertion of resonant posts in some cells of the multi-cell structures. The development of the new damping scheme has been performed using theoretical analysis of the cavity-coupler interaction in conjunction with full-wave electromagnetic (EM) field simulations. This contribution will show the verification of the improved HOM damping performance by measurements on a single section with 11 cells and on the future 33-cell structures. The parasitic impact of the damping scheme on the travelling wave fundamental passband (FPB) will also be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW076

About •

paper received ※ 11 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)

MOPGW077

Impedance Reduction in the CERN SPS Through Element Layout Optimisation

277

A. Farricker, C. Vollinger
CERN, Geneva, Switzerland

The CERN accelerator complex is currently in its long shutdown while the LHC Injector Upgrade is being carried out. The upgrade of the SPS includes but is not limited to: the relocation of the beam dumping system, upgrade of the RF system, replacement of the electrostatic septa and impedance reduction. These major upgrades present an opportunity to perform additional impedance reduction in areas not normally modified due to the large amount of work being performed across the accelerator complex. In this paper, we look at the impedance minimization in the sections near the large aperture quadrupoles of the extraction regions in the CERN SPS. By optimizing the locations of existing equipment and the introduction of a new, more impedance optimised type of bellows, significant reductions in the beam-coupling impedance can be achieved.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW077

About •

paper received ※ 08 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)

WEYPLS1

Building the Impedance Model of a Real Machine

2249

B. Salvant, D. Amorim, S.A. Antipov, S. Arsenyev, M.S. Beck, N. Biancacci, O.S. Brüning, J.V. Campelo, E. Carideo, F. Caspers, A. Farricker, A. Grudiev, T. Kaltenbacher, E. Koukovini-Platia, P. Kramer, A. Lasheen, M. Migliorati, N. Mounet, E. Métral, N. Nasr Esfahani, S. Persichelli, B.K. Popovic, T.L. Rijoff, G. Rumolo, E.N. Shaposhnikova, V.G. Vaccaro, C. Vollinger, N. Wang, C. Zannini, B. Zotter
CERN, Meyrin, Switzerland
D. Amorim
Grenoble-INP Phelma, Grenoble, France
T. Dalascu
EPFL, Lausanne, Switzerland
M. Migliorati
Sapienza University of Rome, Rome, Italy
R. Nagaoka
SOLEIL, Gif-sur-Yvette, France
V.V. Smaluk
BNL, Upton, Long Island, New York, USA
B. Spataro
INFN/LNF, Frascati, Italy
N. Wang
IHEP, Beijing, People’s Republic of China
S.M. White
ESRF, Grenoble, France

A reliable impedance model of a particle accelerator can be built by combining the beam coupling impedances of all the components. This is a necessary step to be able to evaluate the machine performance limitations, identify the main contributors in case an impedance reduction is required, and study the interaction with other mechanisms such as optics nonlinearities, transverse damper, noise, space charge, electron cloud, beam-beam (in a collider). The main phases to create a realistic impedance model, and verify it experimentally, will be reviewed, highlighting the main challenges. Some examples will be presented revealing the levels of precision of machine impedance models that have been achieved.

Slides WEYPLS1 [5.648 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYPLS1

About •

paper received ※ 10 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)