IPAC2017 - List of Authors (Quartullo, D.)

Paper	Title	Page
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)

THPVA023	Studies of Longitudinal Beam Stability in CERN PS Booster After Upgrade	4469
SUSPSIK060	use link to see paper's listing under its alternate paper code
	D. Quartullo, S.C.P. Albright, E.N. Shaposhnikova CERN, Geneva, Switzerland
	The CERN PS Booster, comprised of four superposed rings, is the first synchrotron in the LHC proton injection chain. In 2021, after major upgrades, the injection and extraction beam energies, as well as the acceleration rate, will be increased. The required beam intensities should be a factor of two higher for nominal LHC and fixed-target beams, and the currently used narrow-band ferrite systems will be replaced by broad-band Finemet cavities in all four rings. Future beam stability was investigated using simulations with the Beam Longitudinal Dynamics (BLonD) code. The simulation results for existing situation were compared with beam measurements and gave a good agreement. An accurate impedance model, together with a careful estimation of the longitudinal space charge, was used in simulations of the future acceleration cycle in single and double RF, with phase and radial loops and controlled longitudinal emittance blow-up. Since the beam is not ultra-relativistic and fills the whole ring (h=1), the front and multi-turn back wakes were taken into account, as well as the RF feedbacks which reduce the effect of the Finemet impedance at the revolution frequency harmonics.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA023
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPVA024	Controlled Longitudinal Emittance Blow-Up Using Band-Limited Phase Noise in CERN PSB	4473
	D. Quartullo, E.N. Shaposhnikova, H. Timko CERN, Geneva, Switzerland
	Controlled longitudinal emittance blow-up (from 1 eVs to 1.4 eVs) for LHC beams in the CERN PS Booster is currently achievied using sinusoidal phase modulation of a dedicated high-harmonic RF system. In 2021, after the LHC injectors upgrade, 3 eVs should be extracted to the PS. Even if the current method may satisfy the new requirements, it relies on low-power level RF improvements. In this paper another method of blow-up was considered, that is the injection of band-limited phase noise in the main RF system (h=1), never tried in PSB but already used in CERN SPS and LHC, under different conditions (longer cycles). This technique, which lowers the peak line density and therefore the impact of intensity effects in the PSB and the PS, can also be complementary to the present method. The longitudinal space charge, dominant in the PSB, causes significant synchrotron frequency shifts with intensity, and its effect should be taken into account. Another complication arises from the interaction of the phase loop with the injected noise, since both act on the RF phase. All these elements were studied in simulations of the PSB cycle with the BLonD code, and the required blow-up was achieved.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA024
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

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)

THPVA023

Studies of Longitudinal Beam Stability in CERN PS Booster After Upgrade

4469

SUSPSIK060

use link to see paper's listing under its alternate paper code

D. Quartullo, S.C.P. Albright, E.N. Shaposhnikova
CERN, Geneva, Switzerland

The CERN PS Booster, comprised of four superposed rings, is the first synchrotron in the LHC proton injection chain. In 2021, after major upgrades, the injection and extraction beam energies, as well as the acceleration rate, will be increased. The required beam intensities should be a factor of two higher for nominal LHC and fixed-target beams, and the currently used narrow-band ferrite systems will be replaced by broad-band Finemet cavities in all four rings. Future beam stability was investigated using simulations with the Beam Longitudinal Dynamics (BLonD) code. The simulation results for existing situation were compared with beam measurements and gave a good agreement. An accurate impedance model, together with a careful estimation of the longitudinal space charge, was used in simulations of the future acceleration cycle in single and double RF, with phase and radial loops and controlled longitudinal emittance blow-up. Since the beam is not ultra-relativistic and fills the whole ring (h=1), the front and multi-turn back wakes were taken into account, as well as the RF feedbacks which reduce the effect of the Finemet impedance at the revolution frequency harmonics.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA023

Export •

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

THPVA024

Controlled Longitudinal Emittance Blow-Up Using Band-Limited Phase Noise in CERN PSB

4473

D. Quartullo, E.N. Shaposhnikova, H. Timko
CERN, Geneva, Switzerland

Controlled longitudinal emittance blow-up (from 1 eVs to 1.4 eVs) for LHC beams in the CERN PS Booster is currently achievied using sinusoidal phase modulation of a dedicated high-harmonic RF system. In 2021, after the LHC injectors upgrade, 3 eVs should be extracted to the PS. Even if the current method may satisfy the new requirements, it relies on low-power level RF improvements. In this paper another method of blow-up was considered, that is the injection of band-limited phase noise in the main RF system (h=1), never tried in PSB but already used in CERN SPS and LHC, under different conditions (longer cycles). This technique, which lowers the peak line density and therefore the impact of intensity effects in the PSB and the PS, can also be complementary to the present method. The longitudinal space charge, dominant in the PSB, causes significant synchrotron frequency shifts with intensity, and its effect should be taken into account. Another complication arises from the interaction of the phase loop with the injected noise, since both act on the RF phase. All these elements were studied in simulations of the PSB cycle with the BLonD code, and the required blow-up was achieved.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA024

Export •

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