HB2018 - List of Keywords (impedance)

Paper	Title	Other Keywords	Page
MOA1PL02	Beam Dynamics Challenges for the LHC and Injector Upgrades	emittance, injection, brightness, space-charge	8
	G. Rumolo CERN, Geneva, Switzerland
	The High Luminosity upgrade of the Large Hadron Collider (HL-LHC) will rely on significantly higher bunch current and brightness to meet the future yearly integrated luminosity target. The implications are twofold. On one side, all the accelerators of the LHC injection chain will have to be upgraded to produce the desired beam parameters. For this purpose, the LHC Injectors Upgrade (LIU) program has been established to implement all the needed modifications for meeting the required beam specifications. These upgrades will lead to the lifting of the main intensity and brightness limitations in the injectors, linked to beam instabilities driven by impedance or electron cloud (e-cloud), and space charge. On the other side, the LHC will have to be able to swallow the new beam parameters. This will mainly require control of impedance driven instabilities and beam-beam effects, and e-cloud mitigation. In this paper, we will focus on proton beams by describing the identified performance limitations of the LHC and its injectors, as well as the actions envisioned to overcome them.
	Slides MOA1PL02 [13.138 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-MOA1PL02
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOP2WA03	Experiments and Theory on Beam Stabilization with Second-Order Chromaticity	damping, experiment, betatron, simulation	32
	M. Schenk, X. Buffat, L.R. Carver, K.S.B. Li, E. Métral CERN, Geneva, Switzerland A. Maillard ENS, Paris, France
	This study reports on an alternative method to generate transverse Landau damping to suppress coherent instabilities in circular accelerators. The incoherent betatron tune spread can be produced through detuning with longitudinal rather than transverse action. This approach is motivated by the high-brightness, low transverse emittance beams in future colliders where detuning with transverse amplitude will be less effective. Detuning with longitudinal action can be introduced with a radio frequency (rf) quadrupole, or similarly, using second-order chromaticity. The latter was enhanced in the Large Hadron Collider (LHC) at CERN and experimental results on single-bunch stabilization are briefly recapped. The observations are interpreted analytically by extending the Vlasov formalism to include nonlinear chromaticity. Finally, the newly developed theory is benchmarked against circulant matrix and particle tracking models.
	Slides MOP2WA03 [3.374 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-MOP2WA03
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOP2WA05	Simulation and Measurement of the TMCI Threshold in the LHC	simulation, coupling, operation, synchrotron	43
	D. Amorim, S. A. Antipov, N. Biancacci, X. Buffat, L.R. Carver, E. Métral CERN, Geneva, Switzerland
	The transverse mode coupling instability occurs in individual bunches when two transverse oscillation modes couple at high intensity. Simulations predict an instability threshold in the LHC at a single bunch intensity of 3*10¹¹ protons. The TMCI threshold can be inferred by measuring the tune shift as a function of intensity. This measurement was performed in the LHC for different machine impedances and bunch intensities. The impedance was changed by varying the primary and secondary collimators gaps to increase their contribution to the resistive wall impedance. The experiment also allowed to assess the validity of the LHC impedance model in the single bunch case.
	Slides MOP2WA05 [4.729 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-MOP2WA05
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUP2WE04	Design of the Target Dump Injection Segmented (TDIS) in the Framework of the High Luminosity Large Hadron Collider (HL-LHC) Project	injection, site, shielding, simulation	122
	L. Teofili, D. Carbajo Perez, I. Lamas Garcia, M. Migliorati, A. Perillo CERN, Geneva, Switzerland M. Migliorati INFN-Roma1, Rome, Italy M. Migliorati Sapienza University of Rome, Rome, Italy
	The High Luminosity Large Hadron Collider (HL-LHC) Project at CERN calls for increasing beam brightness and intensity. In this scenario most equipment has to be redesigned and rebuilt. In particular, beam intercepting devices (as dumps, collimators, absorbers and scrapers) have to withstand impact or scraping of the new intense HL-LHC beams without failures. Further, minimizing the electromagnetic beam-device interactions is also a key design driver since they can lead to beam instabilities and excessive thermo-mechanical loading of devices. In this context, the present study assesses the conceptual design quality of the new LHC injection dump, the Target Dump Injection Segmented (TDIS), from an electromagnetic and thermo-mechanical perspective. This contribution analyzes the thermo-mechanical response of the device considering two cases: an accidental beam impact scenario and another accidental scenario with complete failure of the RF-contacts. Further, this paper presents the preliminary results for the simulation of the energy deposited by the two counter-rotating beams circulating in the device.
	Slides TUP2WE04 [10.895 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-TUP2WE04
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUP2WA03	Studies of Capture and Flat-Bottom Losses in the SPS	simulation, optics, injection, beam-loading	180
	M. Schwarz, H. Bartosik, E. Chapochnikova, A. Lasheen, J. Repond, H. Timko CERN, Geneva, Switzerland
	One of the strong limitations for reaching higher beam intensities in the SPS, the injector of the LHC at CERN, are particle losses at flat bottom that increase with beam intensity. In this paper, different sources of these losses are investigated for two available SPS optics, using both measurements and simulations. Part of the losses originate from the PS-to-SPS bunch-to-bucket transfer, because the PS bunches are rotated in longitudinal phase space before injection and do not completely fit into the SPS RF bucket. The injection losses due to different injected bunch distributions were analyzed. Furthermore, at high intensities the transient beam loading in the SPS has a strong impact, which is (partially) compensated by the LLRF system. The effect of the present and future upgraded one-turn delay feedback system and phase loop on flat-bottom losses was studied using the longitudinal tracking code BLonD. Finally, the total particle losses are also affected by limitations in the SPS momentum aperture, visible for higher RF capture voltages in optics with lower transition energy and higher dispersion.
	Slides TUP2WA03 [8.038 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-TUP2WA03
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUP2WA05	Effect of the Extraction Kickers on the Beam Stability in the CERN SPS	kicker, simulation, extraction, cavity	189
	A. Farricker, M.S. Beck, J. Repond, C. Vollinger CERN, Geneva, Switzerland
	Longitudinal beam instability in the CERN SPS is a major limitation in the ability to achieve the bunch intensities required for the goals of the High-Luminosity LHC project (HL-LHC). One of the major drivers in limiting the intensity of the machine is the broadband contribution to the beam-coupling impedance due to the kicker magnets. The extraction kickers (MKE) discussed in this paper are known to give a significant contribution to the overall longitudinal beam-coupling impedance. We present the results of bench measurements of the MKE's impedance to determine the accuracy of electromagnetic simulation models from which the impedance modelused for beam dynamics simulationsis constructed. In addition, we discuss the feasibility and implementation of beam measurements that can indicate the contribution of the MKE magnets to the longitudinal beam-coupling impedance of the SPS.
	Slides TUP2WA05 [2.698 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-TUP2WA05
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEA2WA01	High Intensity Effects of Fixed Target Beams in the CERN Injector Complex	simulation, space-charge, proton, emittance	237
	E. Koukovini-Platia, H. Bartosik, M. Migliorati, G. Rumolo CERN, Geneva, Switzerland M. Migliorati INFN-Roma1, Rome, Italy M. Migliorati Sapienza University of Rome, Rome, Italy
	The current fixed target (FT) experiments at CERN are a complementary approach to the Large Hadron Collider (LHC) and play a crucial role in the investigation of fundamental questions in particle physics. Within the scope of the LHC Injectors Upgrade (LIU), aiming to improve the LHC beam production, the injector complex will be significantly upgraded during the second Long Shutdown (LS2). All non-LHC beams are expected to benefit from these upgrades. In this paper, we focus on the studies of the transverse instability in the Proton Synchrotron (PS), currently limiting the intensity of Time-Of-Flight (ToF) type beams, as well as the prediction of the impact of envisaged hardware modifications. A first discussion on the effect of space charge on the observed instability is also being presented.
	Slides WEA2WA01 [2.483 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-WEA2WA01
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEP2PO003	Beam Loading and Longitudinal Stability Evaluation for the FCC-ee Rings	cavity, beam-loading, feedback, synchrotron	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)

THP2WC01	The FNAL Booster Second Harmonic RF Cavity	cavity, booster, solenoid, cathode	434
	R.L. Madrak, J.E. Dey, K.L. Duel, M.R. Kufer, J. Kuharik, A.V. Makarov, R.D. Padilla, W. Pellico, J. Reid, G.V. Romanov, M. Slabaugh, D. Sun, C.-Y. Tan, I. Terechkine Fermilab, Batavia, Illinois, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DEAC02- 07CH11359 with the United States Department of Energy. A second harmonic RF cavity which uses perpendicularly biased garnet for frequency tuning is currently being constructed for use in the Fermilab Booster. The cavity will operate at twice the fundamental RF frequency, from ~76 - 10⁶ MHz, and will be turned on only during injection, and transition or extraction. Its main purpose is to reduce beam loss as required by Fermilab's Proton Improvement Plan (PIP). After three years of optimization and study, the cavity design has been finalized and all constituent parts have been received. We discuss the design aspects of the cavity and its associated systems, component testing, and status of the cavity construction.
	Slides THP2WC01 [16.734 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THP2WC01
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MOA1PL02

Beam Dynamics Challenges for the LHC and Injector Upgrades

emittance, injection, brightness, space-charge

8

G. Rumolo
CERN, Geneva, Switzerland

The High Luminosity upgrade of the Large Hadron Collider (HL-LHC) will rely on significantly higher bunch current and brightness to meet the future yearly integrated luminosity target. The implications are twofold. On one side, all the accelerators of the LHC injection chain will have to be upgraded to produce the desired beam parameters. For this purpose, the LHC Injectors Upgrade (LIU) program has been established to implement all the needed modifications for meeting the required beam specifications. These upgrades will lead to the lifting of the main intensity and brightness limitations in the injectors, linked to beam instabilities driven by impedance or electron cloud (e-cloud), and space charge. On the other side, the LHC will have to be able to swallow the new beam parameters. This will mainly require control of impedance driven instabilities and beam-beam effects, and e-cloud mitigation. In this paper, we will focus on proton beams by describing the identified performance limitations of the LHC and its injectors, as well as the actions envisioned to overcome them.

Slides MOA1PL02 [13.138 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-MOA1PL02

Export •

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

MOP2WA03

Experiments and Theory on Beam Stabilization with Second-Order Chromaticity

damping, experiment, betatron, simulation

32

M. Schenk, X. Buffat, L.R. Carver, K.S.B. Li, E. Métral
CERN, Geneva, Switzerland
A. Maillard
ENS, Paris, France

This study reports on an alternative method to generate transverse Landau damping to suppress coherent instabilities in circular accelerators. The incoherent betatron tune spread can be produced through detuning with longitudinal rather than transverse action. This approach is motivated by the high-brightness, low transverse emittance beams in future colliders where detuning with transverse amplitude will be less effective. Detuning with longitudinal action can be introduced with a radio frequency (rf) quadrupole, or similarly, using second-order chromaticity. The latter was enhanced in the Large Hadron Collider (LHC) at CERN and experimental results on single-bunch stabilization are briefly recapped. The observations are interpreted analytically by extending the Vlasov formalism to include nonlinear chromaticity. Finally, the newly developed theory is benchmarked against circulant matrix and particle tracking models.

Slides MOP2WA03 [3.374 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-MOP2WA03

Export •

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

MOP2WA05

Simulation and Measurement of the TMCI Threshold in the LHC

simulation, coupling, operation, synchrotron

43

D. Amorim, S. A. Antipov, N. Biancacci, X. Buffat, L.R. Carver, E. Métral
CERN, Geneva, Switzerland

The transverse mode coupling instability occurs in individual bunches when two transverse oscillation modes couple at high intensity. Simulations predict an instability threshold in the LHC at a single bunch intensity of 3*10¹¹ protons. The TMCI threshold can be inferred by measuring the tune shift as a function of intensity. This measurement was performed in the LHC for different machine impedances and bunch intensities. The impedance was changed by varying the primary and secondary collimators gaps to increase their contribution to the resistive wall impedance. The experiment also allowed to assess the validity of the LHC impedance model in the single bunch case.

Slides MOP2WA05 [4.729 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-MOP2WA05

Export •

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

TUP2WE04

Design of the Target Dump Injection Segmented (TDIS) in the Framework of the High Luminosity Large Hadron Collider (HL-LHC) Project

injection, site, shielding, simulation

122

L. Teofili, D. Carbajo Perez, I. Lamas Garcia, M. Migliorati, A. Perillo
CERN, Geneva, Switzerland
M. Migliorati
INFN-Roma1, Rome, Italy
M. Migliorati
Sapienza University of Rome, Rome, Italy

The High Luminosity Large Hadron Collider (HL-LHC) Project at CERN calls for increasing beam brightness and intensity. In this scenario most equipment has to be redesigned and rebuilt. In particular, beam intercepting devices (as dumps, collimators, absorbers and scrapers) have to withstand impact or scraping of the new intense HL-LHC beams without failures. Further, minimizing the electromagnetic beam-device interactions is also a key design driver since they can lead to beam instabilities and excessive thermo-mechanical loading of devices. In this context, the present study assesses the conceptual design quality of the new LHC injection dump, the Target Dump Injection Segmented (TDIS), from an electromagnetic and thermo-mechanical perspective. This contribution analyzes the thermo-mechanical response of the device considering two cases: an accidental beam impact scenario and another accidental scenario with complete failure of the RF-contacts. Further, this paper presents the preliminary results for the simulation of the energy deposited by the two counter-rotating beams circulating in the device.

Slides TUP2WE04 [10.895 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-TUP2WE04

Export •

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

TUP2WA03

Studies of Capture and Flat-Bottom Losses in the SPS

simulation, optics, injection, beam-loading

180

M. Schwarz, H. Bartosik, E. Chapochnikova, A. Lasheen, J. Repond, H. Timko
CERN, Geneva, Switzerland

One of the strong limitations for reaching higher beam intensities in the SPS, the injector of the LHC at CERN, are particle losses at flat bottom that increase with beam intensity. In this paper, different sources of these losses are investigated for two available SPS optics, using both measurements and simulations. Part of the losses originate from the PS-to-SPS bunch-to-bucket transfer, because the PS bunches are rotated in longitudinal phase space before injection and do not completely fit into the SPS RF bucket. The injection losses due to different injected bunch distributions were analyzed. Furthermore, at high intensities the transient beam loading in the SPS has a strong impact, which is (partially) compensated by the LLRF system. The effect of the present and future upgraded one-turn delay feedback system and phase loop on flat-bottom losses was studied using the longitudinal tracking code BLonD. Finally, the total particle losses are also affected by limitations in the SPS momentum aperture, visible for higher RF capture voltages in optics with lower transition energy and higher dispersion.

Slides TUP2WA03 [8.038 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-TUP2WA03

Export •

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

TUP2WA05

Effect of the Extraction Kickers on the Beam Stability in the CERN SPS

kicker, simulation, extraction, cavity

189

A. Farricker, M.S. Beck, J. Repond, C. Vollinger
CERN, Geneva, Switzerland

Longitudinal beam instability in the CERN SPS is a major limitation in the ability to achieve the bunch intensities required for the goals of the High-Luminosity LHC project (HL-LHC). One of the major drivers in limiting the intensity of the machine is the broadband contribution to the beam-coupling impedance due to the kicker magnets. The extraction kickers (MKE) discussed in this paper are known to give a significant contribution to the overall longitudinal beam-coupling impedance. We present the results of bench measurements of the MKE's impedance to determine the accuracy of electromagnetic simulation models from which the impedance modelused for beam dynamics simulationsis constructed. In addition, we discuss the feasibility and implementation of beam measurements that can indicate the contribution of the MKE magnets to the longitudinal beam-coupling impedance of the SPS.

Slides TUP2WA05 [2.698 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-TUP2WA05

Export •

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

WEA2WA01

High Intensity Effects of Fixed Target Beams in the CERN Injector Complex

simulation, space-charge, proton, emittance

237

E. Koukovini-Platia, H. Bartosik, M. Migliorati, G. Rumolo
CERN, Geneva, Switzerland
M. Migliorati
INFN-Roma1, Rome, Italy
M. Migliorati
Sapienza University of Rome, Rome, Italy

The current fixed target (FT) experiments at CERN are a complementary approach to the Large Hadron Collider (LHC) and play a crucial role in the investigation of fundamental questions in particle physics. Within the scope of the LHC Injectors Upgrade (LIU), aiming to improve the LHC beam production, the injector complex will be significantly upgraded during the second Long Shutdown (LS2). All non-LHC beams are expected to benefit from these upgrades. In this paper, we focus on the studies of the transverse instability in the Proton Synchrotron (PS), currently limiting the intensity of Time-Of-Flight (ToF) type beams, as well as the prediction of the impact of envisaged hardware modifications. A first discussion on the effect of space charge on the observed instability is also being presented.

Slides WEA2WA01 [2.483 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-WEA2WA01

Export •

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

WEP2PO003

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

cavity, beam-loading, feedback, synchrotron

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)

THP2WC01

The FNAL Booster Second Harmonic RF Cavity

cavity, booster, solenoid, cathode

434

R.L. Madrak, J.E. Dey, K.L. Duel, M.R. Kufer, J. Kuharik, A.V. Makarov, R.D. Padilla, W. Pellico, J. Reid, G.V. Romanov, M. Slabaugh, D. Sun, C.-Y. Tan, I. Terechkine
Fermilab, Batavia, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DEAC02- 07CH11359 with the United States Department of Energy.
A second harmonic RF cavity which uses perpendicularly biased garnet for frequency tuning is currently being constructed for use in the Fermilab Booster. The cavity will operate at twice the fundamental RF frequency, from ~76 - 10⁶ MHz, and will be turned on only during injection, and transition or extraction. Its main purpose is to reduce beam loss as required by Fermilab's Proton Improvement Plan (PIP). After three years of optimization and study, the cavity design has been finalized and all constituent parts have been received. We discuss the design aspects of the cavity and its associated systems, component testing, and status of the cavity construction.

Slides THP2WC01 [16.734 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THP2WC01

Export •

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