IPAC2017 - List of Authors (Migliorati, M.)

Paper	Title	Page
WEPIK094	LEIR Impedance Model and Coherent Beam Instability Observations	3159
	N. Biancacci, H. Bartosik, A. Huschauer, E. Métral, T.L. Rijoff, B. Salvant, R. Scrivens CERN, Geneva, Switzerland M. Migliorati University of Rome La Sapienza, Rome, Italy
	The LEIR machine is the first synchrotron in the ion acceleration chain at CERN and it is responsible to deliver high intensity ion beams to the LHC. Following the recent progress in the understanding of the intensity limitations, detailed studies of the machine impedance started. In this work we describe the present LEIR impedance model, detailing the contribution to the total longitudinal and transverse impedance of several machine element. We then compare the machine tune shift versus intensity predictions against measurements at injection energy and summarize the coherent instability observations in absence of transverse damper feedback.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK094
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAB020	Coupling Impedances and Collective Effects for FCC-ee	3734
	E. Belli, M. Migliorati University of Rome La Sapienza, Rome, Italy G. Castorina, B. Spataro, M. Zobov INFN/LNF, Frascati (Roma), Italy A. Novokhatski SLAC, Menlo Park, California, USA S. Persichelli LBNL, Berkeley, California, USA
	A very important issue for the Future Circular Collider (FCC) is represented by collective effects due to the self-induced electromagnetic fields, which, acting back on the beam, could produce dangerous instabilities. In this paper we will focus our work on the FCC electron-positron machine: in particular we will study some important sources of wake fields, their coupling impedances and the impact on the beam dynamics. We will also discuss longitudinal and transverse instability thresholds, both for single bunch and multibunch, and indicate some ways to mitigate such instabilities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB020
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPVA022	Comparison of Different Methods to Calculate Induced Voltage in Longitudinal Beam Dynamics Codes	4465
	D. Quartullo, J. Repond CERN, Geneva, Switzerland M. Migliorati University of Rome La Sapienza, Rome, Italy
	Collective effects in longitudinal beam dynamics simulations are essential for many studies since they can perturb the RF potential, giving rise to instabilities. The beam induced voltage can be computed in frequency or time domain using a slicing of the beam profile. This technique is adopted by many codes including CERN BLonD. The slicing acts as a frequency filter and cuts high frequency noise but also physical contributions if the resolution is not sufficient. Moreover, a linear interpolation usually defines the voltage for all the macro-particles, and this can be another source of unphysical effects. The MuSiC code describes interaction between the macro-particles with the wakes generated only by resonator impedances. The complications related to the slices are avoided, but the voltage can contain high frequency noise. In addition, since the computational time scales with the number of resonators and macro-particles, having a large number of them can be cumbersome. In this paper the features of the different approaches are described together with benchmarks between them and analytical formulas, considering both single and multi-turn wakes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA022
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

LEIR Impedance Model and Coherent Beam Instability Observations

3159

N. Biancacci, H. Bartosik, A. Huschauer, E. Métral, T.L. Rijoff, B. Salvant, R. Scrivens
CERN, Geneva, Switzerland
M. Migliorati
University of Rome La Sapienza, Rome, Italy

The LEIR machine is the first synchrotron in the ion acceleration chain at CERN and it is responsible to deliver high intensity ion beams to the LHC. Following the recent progress in the understanding of the intensity limitations, detailed studies of the machine impedance started. In this work we describe the present LEIR impedance model, detailing the contribution to the total longitudinal and transverse impedance of several machine element. We then compare the machine tune shift versus intensity predictions against measurements at injection energy and summarize the coherent instability observations in absence of transverse damper feedback.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK094

Export •

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

THPAB020

Coupling Impedances and Collective Effects for FCC-ee

3734

E. Belli, M. Migliorati
University of Rome La Sapienza, Rome, Italy
G. Castorina, B. Spataro, M. Zobov
INFN/LNF, Frascati (Roma), Italy
A. Novokhatski
SLAC, Menlo Park, California, USA
S. Persichelli
LBNL, Berkeley, California, USA

A very important issue for the Future Circular Collider (FCC) is represented by collective effects due to the self-induced electromagnetic fields, which, acting back on the beam, could produce dangerous instabilities. In this paper we will focus our work on the FCC electron-positron machine: in particular we will study some important sources of wake fields, their coupling impedances and the impact on the beam dynamics. We will also discuss longitudinal and transverse instability thresholds, both for single bunch and multibunch, and indicate some ways to mitigate such instabilities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB020

Export •

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

THPVA022

Comparison of Different Methods to Calculate Induced Voltage in Longitudinal Beam Dynamics Codes

4465

D. Quartullo, J. Repond
CERN, Geneva, Switzerland
M. Migliorati
University of Rome La Sapienza, Rome, Italy

Collective effects in longitudinal beam dynamics simulations are essential for many studies since they can perturb the RF potential, giving rise to instabilities. The beam induced voltage can be computed in frequency or time domain using a slicing of the beam profile. This technique is adopted by many codes including CERN BLonD. The slicing acts as a frequency filter and cuts high frequency noise but also physical contributions if the resolution is not sufficient. Moreover, a linear interpolation usually defines the voltage for all the macro-particles, and this can be another source of unphysical effects. The MuSiC code describes interaction between the macro-particles with the wakes generated only by resonator impedances. The complications related to the slices are avoided, but the voltage can contain high frequency noise. In addition, since the computational time scales with the number of resonators and macro-particles, having a large number of them can be cumbersome. In this paper the features of the different approaches are described together with benchmarks between them and analytical formulas, considering both single and multi-turn wakes.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA022

Export •

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