IPAC2019 - List of Authors (Shaposhnikova, E.N.)

Paper	Title	Page
MOPGW069	Recent Beam Performance Achievements with the Pb-Ion Beam in the SPS for LHC Physics Runs	250
	H. Bartosik, R. Alemany-Fernández, T. Argyropoulos, T. Bohl, H. Damerau, V. Kain, G. Papotti, G. Rumolo, Á. Saá Hernández, E.N. Shaposhnikova CERN, Geneva, Switzerland
	In the SPS, which is the last accelerator in the LHC ion injector chain, multiple injections of the Pb-ion beam have to be accumulated. On this injection plateau the beam suffers from considerable degradation such as emittance growth and losses. This paper summarises the achievements on improving the beam parameters and maximising the performance of the Pb-ion beam for the LHC physics run in 2018. The results are discussed in view of the target beam parameters of the LHC injectors upgrade project, which is being deployed during the presently ongoing long shutdown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW069
About •	paper received ※ 12 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPGW070	Longitudinal Stability of the Hollow Ion Bunches After Momentum Slip-Stacking in the CERN SPS	254
	T. Argyropoulos, A. Lasheen, D. Quartullo, E.N. Shaposhnikova CERN, Geneva, Switzerland
	Momentum slip-stacking is planned to be used for the lead ion beams in the CERN SPS to double the beam intensity for the High-Luminosity LHC project. During this RF manipulation two SPS batches, controlled by two independent RF systems, are going to be interleaved on an intermediate energy plateau, reducing the bunch spacing from 100 to 50 ns. However, there are limitations how close the frequencies of two RF systems can approach each other, resulting in a hole in the longitudinal bunch particle distribution due to the offset in energy of the recaptured bunches. After filamentation, these bunches should be further accelerated to the SPS top energy, before extraction to the LHC. Macro-particle simulations have shown that Landau damping is lost for the bunches with the smallest longitudinal emittances in the batch, causing un-damped oscillations of the bunch core after recapture. The standard application of an additional, fourth harmonic RF system, successfully used in proton operation, was not able to damp the oscillations at top energy, while it was necessary to switch it on from the moment of recapture. In this paper the longitudinal stability of the bunches after slip-stacking is studied in more details both by macro-particle simulations and analytical calculations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW070
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPGW083	Longitudinal Coupled-Bunch Instability Evaluation for FCC-hh	297
	I. Karpov, E.N. Shaposhnikova CERN, Geneva, Switzerland
	High-order modes (HOM) of the accelerating rf structures and other machine elements, if not sufficiently damped, can drive longitudinal coupled-bunch instabilities (CBI). Their thresholds can be accurately obtained from macro-particle simulations using the detailed impedance model containing many different contributions. This method, however, is very difficult to apply for synchrotrons with a large number of bunches, as it is the case for the Future Circular hadron-hadron Collider (FCC-hh) with up to 10400 circulating bunches per beam. In this paper the semi-analytical approach is used for calculations of the instability thresholds during the acceleration cycle of the FCC-hh. As the result, we define requirements for the HOM damping that would be sufficient to prevent development of longitudinal CBI in the presence of weak synchrotron radiation damping.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW083
About •	paper received ※ 13 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)

MOPGW091	Capture and Flat-Bottom Losses in the CERN SPS	327
	M. Schwarz, A. Lasheen, G. Papotti, J. Repond, E.N. Shaposhnikova, H. Timko CERN, Meyrin, Switzerland
	Particle losses on the flat bottom of the SPS, the last accelerator in the injector chain of the LHC at CERN, are a strong limitation for reaching the high intensities required by the high luminosity upgrade of the LHC. Two contributions to these losses are investigated in this paper. The first losses occur during the PS-to-SPS bunch-to-bucket transfer, since the bunch rotation in the PS creates halo particles and the bunch does not completely fit into the SPS RF-bucket. The effect of longitudinal shaving in the PS on the beam transmission was recently tested. At high intensities, further capture losses are caused by beam loading in the traveling wave RF system of the SPS, which is partially compensated by the LLRF system, in particular by one-turn delay feedback. While the feedforward system reduces the capture losses, it also increases the losses along the flat bottom due to the RF noise.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW091
About •	paper received ※ 09 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMP037	Updated High-Energy LHC Design	524
	F. Zimmermann, D. Amorim, S.A. Antipov, S. Arsenyev, M. Benedikt, R. Bruce, M.P. Crouch, S.D. Fartoukh, M. Giovannozzi, B. Goddard, M. Hofer, J. Keintzel, R. Kersevan, V. Mertens, J. Molson, Y. Muttoni, J.A. Osborne, V. Parma, V. Raginel, S. Redaelli, T. Risselada, I. Ruehl, B. Salvant, D. Schoerling, E.N. Shaposhnikova, L.J. Tavian, E. Todesco, R. Tomás, D. Tommasini, F. Valchkova-Georgieva, V. Venturi, D. Wollmann CERN, Geneva, Switzerland J.L. Abelleira, A. Abramov, E. Cruz Alaniz, H. Pikhartova, A. Seryi, L. van Riesen-Haupt JAI, Oxford, United Kingdom A. Apyan ANSL, Yerevan, Armenia J. Barranco García, L. Mether, T. Pieloni, L. Rivkin, C. Tambasco EPFL, Lausanne, Switzerland F. Burkart DESY, Hamburg, Germany Y. Cai, Y.M. Nosochkov SLAC, Menlo Park, California, USA G. Guillermo Cantón CINVESTAV, Mérida, Mexico K. Ohmi, K. Oide, D. Zhou KEK, Ibaraki, Japan
	Funding: This work was supported in part by the European Commission under the HORIZON 2020 project ARIES no.730871, and by the Swiss Accelerator Research and Technology collaboration CHART. We present updated design parameters for a future High-Energy LHC. A more realistic turnaround time has led to a revision of the target peak luminosity, as well as a choice of a larger IP beta function, and longer physics fills. Pushed parameters of the Nb₃Sn superconducting cable together with a modified layout of the 16 T dipole magnets resulted in revised field errors, updated dynamic-aperture simulations, and an associated re-evaluation of injector options. Collimators in the dispersion suppressors help achieve satisfactory cleaning performance. Longitudinal beam parameters ensure beam stability throughout the cycle. Intrabeam scattering rates and Touschek lifetime appear benign.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP037
About •	paper received ※ 10 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)

WEPTS039	Momentum Slip-Stacking in CERN SPS for the Ion Beams	3184
	T. Argyropoulos, T. Bohl, A. Lasheen, G. Papotti, D. Quartullo, E.N. Shaposhnikova CERN, Geneva, Switzerland
	The LHC Injectors Upgrade (LIU) project at CERN aims at doubling the total intensity of the lead ion beam for the High-Luminosity (HL) LHC. Achieving this goal requires using momentum slip-stacking in the SPS, the LHC injector. Slip-stacking will be applied on an intermediate energy plateau to interleave two batches, reducing the bunch spacing from 100 ns to 50 ns and thus increasing the total number of bunches injected into the LHC. Realistic macro-particle simulations, with the present SPS impedance model are used to study and design this complicated beam manipulation. Slip-stacking can be tested experimentally only after the upgrade of the SPS 200 MHz RF system, in 2021. Preliminary, slip-stacking related beam measurements were performed at the end of 2018. In this paper both macro-particle simulations and beam measurements are reported with emphasis given on optimisation of the process, crucial to achieve the required HL-LHC parameters (bunch lengths, beam losses).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS039
About •	paper received ※ 15 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)

WEPTS049	Flat-Bottom Instabilities in the CERN SPS	3224
	M. Schwarz, K. Iliakis, A. Lasheen, G. Papotti, J. Repond, E.N. Shaposhnikova, H. Timko CERN, Meyrin, Switzerland
	At beam intensities of 2.6·10¹¹ protons per bunch, required at SPS injection for the High Luminosity LHC beam, longitudinal instabilities can degrade the beam quality delivered by the SPS, the LHC injector at CERN. In this paper, we concentrate on beam instability at flat bottom. The dependence of the instability threshold on longitudinal emittance and LLRF system settings was measured, to help identify the impedance driving this instability. While reducing the longitudinal emittance reduces the losses at injection, it can drive the beam unstable. The LLRF system of the SPS (partially) compensates beam loading, but also affects the instability. The effect of the different LLRF systems (feedback, feedforward, phase loop and longitudinal damper) and fourth harmonic RF system on the instability was investigated. The measurements are compared with simulations performed with the longitudinal tracking code BLonD.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS049
About •	paper received ※ 10 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THXPLM1	LHC Injectors Upgrade Project: Towards New Territory Beam Parameters	3385
	M. Meddahi, R. Alemany-Fernández, H. Bartosik, G. Bellodi, J. Coupard, H. Damerau, G.P. Di Giovanni, F.B. Dos Santos Pedrosa, A. Funken, B. Goddard, K. Hanke, A. Huschauer, V. Kain, A.M. Lombardi, B. Mikulec, S. Prodon, G. Rumolo, R. Scrivens, E.N. Shaposhnikova CERN, Geneva, Switzerland
	The LHC injectors Upgrade (LIU) project aims at increasing the intensity and brightness in the LHC injectors in order to match the challenging requirements of the High-Luminosity LHC (HL-LHC) project, while ensuring high availability and reliable operation of the injectors complex up to the end of the HL-LHC era (ca. 2035). This requires extensive hardware modifications and new beam dynamics solutions in the entire LHC proton and ion injection chains: the new Linac4, the Proton Synchrotron Booster, the Proton Synchrotron the Super Proton Synchrotron together with the ion PS injectors (the Linac3 and the Low Energy Ion Ring). All hardware modifications will be implemented during the 2019-2020 CERN accelerators shutdown. This talk would analyze the various project phases, share the lessons learned, and conclude on the expected beam parameter reach, together with the related risks.
	Slides THXPLM1 [20.029 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THXPLM1
About •	paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Recent Beam Performance Achievements with the Pb-Ion Beam in the SPS for LHC Physics Runs

250

H. Bartosik, R. Alemany-Fernández, T. Argyropoulos, T. Bohl, H. Damerau, V. Kain, G. Papotti, G. Rumolo, Á. Saá Hernández, E.N. Shaposhnikova
CERN, Geneva, Switzerland

In the SPS, which is the last accelerator in the LHC ion injector chain, multiple injections of the Pb-ion beam have to be accumulated. On this injection plateau the beam suffers from considerable degradation such as emittance growth and losses. This paper summarises the achievements on improving the beam parameters and maximising the performance of the Pb-ion beam for the LHC physics run in 2018. The results are discussed in view of the target beam parameters of the LHC injectors upgrade project, which is being deployed during the presently ongoing long shutdown.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW069

About •

paper received ※ 12 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019

Export •

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

MOPGW070

Longitudinal Stability of the Hollow Ion Bunches After Momentum Slip-Stacking in the CERN SPS

254

T. Argyropoulos, A. Lasheen, D. Quartullo, E.N. Shaposhnikova
CERN, Geneva, Switzerland

Momentum slip-stacking is planned to be used for the lead ion beams in the CERN SPS to double the beam intensity for the High-Luminosity LHC project. During this RF manipulation two SPS batches, controlled by two independent RF systems, are going to be interleaved on an intermediate energy plateau, reducing the bunch spacing from 100 to 50 ns. However, there are limitations how close the frequencies of two RF systems can approach each other, resulting in a hole in the longitudinal bunch particle distribution due to the offset in energy of the recaptured bunches. After filamentation, these bunches should be further accelerated to the SPS top energy, before extraction to the LHC. Macro-particle simulations have shown that Landau damping is lost for the bunches with the smallest longitudinal emittances in the batch, causing un-damped oscillations of the bunch core after recapture. The standard application of an additional, fourth harmonic RF system, successfully used in proton operation, was not able to damp the oscillations at top energy, while it was necessary to switch it on from the moment of recapture. In this paper the longitudinal stability of the bunches after slip-stacking is studied in more details both by macro-particle simulations and analytical calculations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW070

About •

paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

Export •

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

MOPGW083

Longitudinal Coupled-Bunch Instability Evaluation for FCC-hh

297

I. Karpov, E.N. Shaposhnikova
CERN, Geneva, Switzerland

High-order modes (HOM) of the accelerating rf structures and other machine elements, if not sufficiently damped, can drive longitudinal coupled-bunch instabilities (CBI). Their thresholds can be accurately obtained from macro-particle simulations using the detailed impedance model containing many different contributions. This method, however, is very difficult to apply for synchrotrons with a large number of bunches, as it is the case for the Future Circular hadron-hadron Collider (FCC-hh) with up to 10400 circulating bunches per beam. In this paper the semi-analytical approach is used for calculations of the instability thresholds during the acceleration cycle of the FCC-hh. As the result, we define requirements for the HOM damping that would be sufficient to prevent development of longitudinal CBI in the presence of weak synchrotron radiation damping.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW083

About •

paper received ※ 13 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)

MOPGW091

Capture and Flat-Bottom Losses in the CERN SPS

327

M. Schwarz, A. Lasheen, G. Papotti, J. Repond, E.N. Shaposhnikova, H. Timko
CERN, Meyrin, Switzerland

Particle losses on the flat bottom of the SPS, the last accelerator in the injector chain of the LHC at CERN, are a strong limitation for reaching the high intensities required by the high luminosity upgrade of the LHC. Two contributions to these losses are investigated in this paper. The first losses occur during the PS-to-SPS bunch-to-bucket transfer, since the bunch rotation in the PS creates halo particles and the bunch does not completely fit into the SPS RF-bucket. The effect of longitudinal shaving in the PS on the beam transmission was recently tested. At high intensities, further capture losses are caused by beam loading in the traveling wave RF system of the SPS, which is partially compensated by the LLRF system, in particular by one-turn delay feedback. While the feedforward system reduces the capture losses, it also increases the losses along the flat bottom due to the RF noise.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW091

About •

paper received ※ 09 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

Export •

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

MOPMP037

Updated High-Energy LHC Design

524

F. Zimmermann, D. Amorim, S.A. Antipov, S. Arsenyev, M. Benedikt, R. Bruce, M.P. Crouch, S.D. Fartoukh, M. Giovannozzi, B. Goddard, M. Hofer, J. Keintzel, R. Kersevan, V. Mertens, J. Molson, Y. Muttoni, J.A. Osborne, V. Parma, V. Raginel, S. Redaelli, T. Risselada, I. Ruehl, B. Salvant, D. Schoerling, E.N. Shaposhnikova, L.J. Tavian, E. Todesco, R. Tomás, D. Tommasini, F. Valchkova-Georgieva, V. Venturi, D. Wollmann
CERN, Geneva, Switzerland
J.L. Abelleira, A. Abramov, E. Cruz Alaniz, H. Pikhartova, A. Seryi, L. van Riesen-Haupt
JAI, Oxford, United Kingdom
A. Apyan
ANSL, Yerevan, Armenia
J. Barranco García, L. Mether, T. Pieloni, L. Rivkin, C. Tambasco
EPFL, Lausanne, Switzerland
F. Burkart
DESY, Hamburg, Germany
Y. Cai, Y.M. Nosochkov
SLAC, Menlo Park, California, USA
G. Guillermo Cantón
CINVESTAV, Mérida, Mexico
K. Ohmi, K. Oide, D. Zhou
KEK, Ibaraki, Japan

Funding: This work was supported in part by the European Commission under the HORIZON 2020 project ARIES no.730871, and by the Swiss Accelerator Research and Technology collaboration CHART.
We present updated design parameters for a future High-Energy LHC. A more realistic turnaround time has led to a revision of the target peak luminosity, as well as a choice of a larger IP beta function, and longer physics fills. Pushed parameters of the Nb₃Sn superconducting cable together with a modified layout of the 16 T dipole magnets resulted in revised field errors, updated dynamic-aperture simulations, and an associated re-evaluation of injector options. Collimators in the dispersion suppressors help achieve satisfactory cleaning performance. Longitudinal beam parameters ensure beam stability throughout the cycle. Intrabeam scattering rates and Touschek lifetime appear benign.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP037

About •

paper received ※ 10 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)

WEPTS039

Momentum Slip-Stacking in CERN SPS for the Ion Beams

3184

T. Argyropoulos, T. Bohl, A. Lasheen, G. Papotti, D. Quartullo, E.N. Shaposhnikova
CERN, Geneva, Switzerland

The LHC Injectors Upgrade (LIU) project at CERN aims at doubling the total intensity of the lead ion beam for the High-Luminosity (HL) LHC. Achieving this goal requires using momentum slip-stacking in the SPS, the LHC injector. Slip-stacking will be applied on an intermediate energy plateau to interleave two batches, reducing the bunch spacing from 100 ns to 50 ns and thus increasing the total number of bunches injected into the LHC. Realistic macro-particle simulations, with the present SPS impedance model are used to study and design this complicated beam manipulation. Slip-stacking can be tested experimentally only after the upgrade of the SPS 200 MHz RF system, in 2021. Preliminary, slip-stacking related beam measurements were performed at the end of 2018. In this paper both macro-particle simulations and beam measurements are reported with emphasis given on optimisation of the process, crucial to achieve the required HL-LHC parameters (bunch lengths, beam losses).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS039

About •

paper received ※ 15 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)

WEPTS049

Flat-Bottom Instabilities in the CERN SPS

3224

M. Schwarz, K. Iliakis, A. Lasheen, G. Papotti, J. Repond, E.N. Shaposhnikova, H. Timko
CERN, Meyrin, Switzerland

At beam intensities of 2.6·10¹¹ protons per bunch, required at SPS injection for the High Luminosity LHC beam, longitudinal instabilities can degrade the beam quality delivered by the SPS, the LHC injector at CERN. In this paper, we concentrate on beam instability at flat bottom. The dependence of the instability threshold on longitudinal emittance and LLRF system settings was measured, to help identify the impedance driving this instability. While reducing the longitudinal emittance reduces the losses at injection, it can drive the beam unstable. The LLRF system of the SPS (partially) compensates beam loading, but also affects the instability. The effect of the different LLRF systems (feedback, feedforward, phase loop and longitudinal damper) and fourth harmonic RF system on the instability was investigated. The measurements are compared with simulations performed with the longitudinal tracking code BLonD.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS049

About •

paper received ※ 10 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

Export •

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

THXPLM1

LHC Injectors Upgrade Project: Towards New Territory Beam Parameters

3385

M. Meddahi, R. Alemany-Fernández, H. Bartosik, G. Bellodi, J. Coupard, H. Damerau, G.P. Di Giovanni, F.B. Dos Santos Pedrosa, A. Funken, B. Goddard, K. Hanke, A. Huschauer, V. Kain, A.M. Lombardi, B. Mikulec, S. Prodon, G. Rumolo, R. Scrivens, E.N. Shaposhnikova
CERN, Geneva, Switzerland

The LHC injectors Upgrade (LIU) project aims at increasing the intensity and brightness in the LHC injectors in order to match the challenging requirements of the High-Luminosity LHC (HL-LHC) project, while ensuring high availability and reliable operation of the injectors complex up to the end of the HL-LHC era (ca. 2035). This requires extensive hardware modifications and new beam dynamics solutions in the entire LHC proton and ion injection chains: the new Linac4, the Proton Synchrotron Booster, the Proton Synchrotron the Super Proton Synchrotron together with the ion PS injectors (the Linac3 and the Low Energy Ion Ring). All hardware modifications will be implemented during the 2019-2020 CERN accelerators shutdown. This talk would analyze the various project phases, share the lessons learned, and conclude on the expected beam parameter reach, together with the related risks.

Slides THXPLM1 [20.029 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THXPLM1

About •

paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

Export •

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