IPAC2015 - List of Authors (Iadarola, G.)

Paper	Title	Page
MOPJE048	Electron-Cloud Studies for Transversely Split Beams	399
	N. Pradhan, S.S. Gilardoni, M. Giovannozzi, G. Iadarola, G. Rumolo CERN, Geneva, Switzerland N. Pradhan UMiss, University, Mississippi, USA
	Recently, resonance crossing has been proposed as a means of manipulating the transverse beam distribution. This technique has application, among other topics, to injection and extraction schemes. Moreover, the transversely split beams might also be used as a mitigation measure of electron-cloud effects. The results of detailed numerical simulations are discussed in this paper, possibly opening new options for scrubbing of beam pipes in circular accelerators.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE048
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MOPJE049	Benchmarking the CERN-SPS Transverse Impedance Model with Measured Headtail Growth Rates	402
	C. Zannini, H. Bartosik, G. Iadarola, G. Rumolo, B. Salvant CERN, Geneva, Switzerland
	The latest SPS transverse impedance model includes kicker magnets, wall impedance, transition pieces (e.g. flanges and vacuum chamber discontinuities), beam position monitors and RF cavities. The model has already been successfully benchmarked against coherent tune shift and transverse mode coupling instability measurements. In this paper we present measurements of the headtail growth rates for a wide range of negative chromaticities and for two different configurations of machine optics (nominal and low gamma transition). The measurement results are compared with HEADTAIL simulations using the wake fields obtained from the SPS transverse impedance model.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE049
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MOPJE050	Transverse Impedance Model of the CERN-PSB	406
	C. Zannini, G. Iadarola, K.S.B. Li, T.L. Rijoff, G. Rumolo CERN, Geneva, Switzerland B. Jones STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom T.L. Rijoff TU Darmstadt, Darmstadt, Germany
	In the framework of the PS-Booster upgrade project an accurate impedance model is needed in order to determine the effect on the beam stability and assess the impact of the new devices before installation in the machine. This paper describes the PSB impedance model which includes resistive wall, indirect space charge, flanges, step transitions, ejection kicker including cables, injection kickers and cavities. Each impedance contribution has been computed for different energies in the PSB cycle. Measurements of the coherent tune shifts have been performed and compared to calculations based on the impedance model.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE050
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MOPJE051	Effect of Electron Cloud in Quadrupoles on Beam Instability	409
	G. Iadarola, A.P. Axford, H. Bartosik, K.S.B. Li, G. Rumolo CERN, Geneva, Switzerland
	Both simulations and machine experience at the CERN-SPS and LHC have shown that the electron cloud has a lower build up threshold in quadrupoles than in dipoles and field free regions. As a consequence, while beam induced scrubbing can efficiently suppress the electron cloud in both dipoles and field free regions, a residual electron cloud can still survive in the quadrupoles and potentially degrade the beam quality. To study this effect, a PyECLOUD module for electron tracking in quadrupole fields including effects of secondary emission at the vacuum chamber has been implemented in PyHEADTAIL. With this module, the effect of the electron cloud in quadrupoles on beam stability and beam quality preservation can be assessed, as well as its impact on future LHC and HL-LHC operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE051
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WEPHA002	Electromagnetic Characterization of NEG Properties Above 200 GHz for the CLIC Damping Rings	3097
	E. Koukovini-Platia, G. Iadarola, G. Rumolo, C. Zannini CERN, Geneva, Switzerland
	Non-Evaporable Getter (NEG) will be used in the CLIC electron damping rings (EDR) to suppress fast beam ion instabilities due to its effective pumping ability. The electromagnetic (EM) characterization of the NEG properties up to high frequencies is required for the correct impedance modeling of the DR components. The properties are determined using WR-3.4 and WR-1.5 rectangular waveguides, based on a combination of experimental measurements of the complex transmission coefficient S21 with a Vector Network Analyzer (VNA) and CST 3D EM simulations, for the frequency range of 220-330 GHz and 500-750 GHz. The results obtained using NEG-coated Aluminum (Al) waveguides are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA002
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THPF091	Detailed Studies of Beam Induced Scrubbing in the CERN-SPS	3908
	G. Iadarola, H. Bartosik, T. Bohl, B. Goddard, G. Kotzian, K.S.B. Li, L. Mether, G. Rumolo, M. Schenk, E.N. Shaposhnikova, M. Taborelli CERN, Geneva, Switzerland
	In the framework of the LHC Injectors Upgrade (LIU) program, it is foreseen to take all the necessary measures to avoid electron cloud effects in the CERN-SPS. This can be achieved by either relying on beam induced scrubbing or by coating the vacuum chambers with intrinsically low Secondary Electron Yield (SEY) material over a large fraction of the ring. To clearly establish the potential of beam induced scrubbing, and to eventually decide between the two above options, an extensive scrubbing campaign is taking place at the SPS. Ten days in 2014 and two full weeks in 2015 are devoted to machine scrubbing and scrubbing qualification studies. This paper summarizes the main findings in terms of scrubbing efficiency and reach so far, addressing also the option of using a special doublet beam and its implication for LHC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF091
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Paper

Title

Page

Electron-Cloud Studies for Transversely Split Beams

399

N. Pradhan, S.S. Gilardoni, M. Giovannozzi, G. Iadarola, G. Rumolo
CERN, Geneva, Switzerland
N. Pradhan
UMiss, University, Mississippi, USA

Recently, resonance crossing has been proposed as a means of manipulating the transverse beam distribution. This technique has application, among other topics, to injection and extraction schemes. Moreover, the transversely split beams might also be used as a mitigation measure of electron-cloud effects. The results of detailed numerical simulations are discussed in this paper, possibly opening new options for scrubbing of beam pipes in circular accelerators.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE048

Export •

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

MOPJE049

Benchmarking the CERN-SPS Transverse Impedance Model with Measured Headtail Growth Rates

402

C. Zannini, H. Bartosik, G. Iadarola, G. Rumolo, B. Salvant
CERN, Geneva, Switzerland

The latest SPS transverse impedance model includes kicker magnets, wall impedance, transition pieces (e.g. flanges and vacuum chamber discontinuities), beam position monitors and RF cavities. The model has already been successfully benchmarked against coherent tune shift and transverse mode coupling instability measurements. In this paper we present measurements of the headtail growth rates for a wide range of negative chromaticities and for two different configurations of machine optics (nominal and low gamma transition). The measurement results are compared with HEADTAIL simulations using the wake fields obtained from the SPS transverse impedance model.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE049

Export •

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

MOPJE050

Transverse Impedance Model of the CERN-PSB

406

C. Zannini, G. Iadarola, K.S.B. Li, T.L. Rijoff, G. Rumolo
CERN, Geneva, Switzerland
B. Jones
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
T.L. Rijoff
TU Darmstadt, Darmstadt, Germany

In the framework of the PS-Booster upgrade project an accurate impedance model is needed in order to determine the effect on the beam stability and assess the impact of the new devices before installation in the machine. This paper describes the PSB impedance model which includes resistive wall, indirect space charge, flanges, step transitions, ejection kicker including cables, injection kickers and cavities. Each impedance contribution has been computed for different energies in the PSB cycle. Measurements of the coherent tune shifts have been performed and compared to calculations based on the impedance model.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE050

Export •

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

MOPJE051

Effect of Electron Cloud in Quadrupoles on Beam Instability

409

G. Iadarola, A.P. Axford, H. Bartosik, K.S.B. Li, G. Rumolo
CERN, Geneva, Switzerland

Both simulations and machine experience at the CERN-SPS and LHC have shown that the electron cloud has a lower build up threshold in quadrupoles than in dipoles and field free regions. As a consequence, while beam induced scrubbing can efficiently suppress the electron cloud in both dipoles and field free regions, a residual electron cloud can still survive in the quadrupoles and potentially degrade the beam quality. To study this effect, a PyECLOUD module for electron tracking in quadrupole fields including effects of secondary emission at the vacuum chamber has been implemented in PyHEADTAIL. With this module, the effect of the electron cloud in quadrupoles on beam stability and beam quality preservation can be assessed, as well as its impact on future LHC and HL-LHC operation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE051

Export •

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

WEPHA002

Electromagnetic Characterization of NEG Properties Above 200 GHz for the CLIC Damping Rings

3097

E. Koukovini-Platia, G. Iadarola, G. Rumolo, C. Zannini
CERN, Geneva, Switzerland

Non-Evaporable Getter (NEG) will be used in the CLIC electron damping rings (EDR) to suppress fast beam ion instabilities due to its effective pumping ability. The electromagnetic (EM) characterization of the NEG properties up to high frequencies is required for the correct impedance modeling of the DR components. The properties are determined using WR-3.4 and WR-1.5 rectangular waveguides, based on a combination of experimental measurements of the complex transmission coefficient S21 with a Vector Network Analyzer (VNA) and CST 3D EM simulations, for the frequency range of 220-330 GHz and 500-750 GHz. The results obtained using NEG-coated Aluminum (Al) waveguides are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA002

Export •

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

THPF091

Detailed Studies of Beam Induced Scrubbing in the CERN-SPS

3908

G. Iadarola, H. Bartosik, T. Bohl, B. Goddard, G. Kotzian, K.S.B. Li, L. Mether, G. Rumolo, M. Schenk, E.N. Shaposhnikova, M. Taborelli
CERN, Geneva, Switzerland

In the framework of the LHC Injectors Upgrade (LIU) program, it is foreseen to take all the necessary measures to avoid electron cloud effects in the CERN-SPS. This can be achieved by either relying on beam induced scrubbing or by coating the vacuum chambers with intrinsically low Secondary Electron Yield (SEY) material over a large fraction of the ring. To clearly establish the potential of beam induced scrubbing, and to eventually decide between the two above options, an extensive scrubbing campaign is taking place at the SPS. Ten days in 2014 and two full weeks in 2015 are devoted to machine scrubbing and scrubbing qualification studies. This paper summarizes the main findings in terms of scrubbing efficiency and reach so far, addressing also the option of using a special doublet beam and its implication for LHC.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF091

Export •

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