E. Métral

European Organization for Nuclear Research

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Benoît Salvant

European Organization for Nuclear Research

130

G. Arduini

European Organization for Nuclear Research

G. Rumolo

European Organization for Nuclear Research

Nicolò Biancacci

European Organization for Nuclear Research

Xavier Buffat

European Organization for Nuclear Research

Stefano Redaelli

European Organization for Nuclear Research

M. Giovannozzi

European Organization for Nuclear Research

Tatiana Pieloni

European Organization for Nuclear Research

S. Gilardoni

European Organization for Nuclear Research

Nicolas Mounet

European Organization for Nuclear Research

Cooperative Institutions

European Organization for Nuclear Research

1,004

Fermi National Accelerator Laboratory

151

Istituto Nazionale di Fisica Nucleare

138

A. Alikhanyan National Laboratory

119

Institute of High Energy Physics

113

Brookhaven National Laboratory

108

Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati

100

Istituto Nazionale di Fisica Nucleare, Sezione di Roma I

Centre National de la Recherche Scientifique

Lawrence Berkeley National Laboratory

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THE FAST VERTICAL SINGLE-BUNCH INSTABILITY AFTER INJECTION INTO THE CERN SUPER PROTON SYNCHROTRON

E. Métral G. Arduini Thomas Bohl H. Burkhardt G. Rumolo

Since 2003, high-intensity single-bunch proton beams with low longitudinal emittance have been affected by heavy losses after less than one synchrotron period after injection. The effects of the resonance frequency of the responsible impedance, longitudinal emittance and chromaticity on the intensity threshold were already discussed in detail in 2004, comparing analytical predictions with simulation results. In this paper the evolution of the instability between injection and the time of beam loss is our main concern. Measurements are compared with HEADTAIL simulations. A travellingwave pattern propagating along the bunch, which is the signature of a Beam Break-Up or Transverse Mode Coupling Instability (TMCI), is clearly identified. The oscillating frequency, near ~1 GHz, is in good agreement with the usual broad-band impedance model deduced from beam-based measurements like the head-tail growth rate vs. chromaticity.

Proton Synchrotron

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Final Results from the Novel Multi-Turn Extraction Studies at CERN Proton Synchrotron

Proceedings of the 2003 Particle Accelerator Conference (2006)

R. Cappi S. Gilardoni M. Giovannozzi M. Martini E. Métral

Recently a novel approach to perform multi-turn extraction was proposed based on beam splitting in the transverse phase space by means of trapping inside stable islands. An experimental campaign was launched since the year 2002 to assess the feasibility of such an extraction scheme at the CERN Proton Synchrotron. During the year 2004 run, a high-intensity single-bunch beam was successfully split and the generated beamlets separated without any measurable losses. The latest experimental results are presented and discussed in details in this paper. These achievements represent a substantial step forward with respect to what achieved in previous years, as only a low-intensity bunch could be split without losses. Furthermore, this opens the possibility of using such a technique for routine operation with the high-intensity proton beams required for the planned CERN Neutrino to Gran Sasso Project.

Super Proton Synchrotron

Proton Synchrotron

Intensity

10.1109/pac.2005.1590378

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Transverse impendance of LHC collimators

E. Métral G. Arduini R. Aßmann Andrea Boccardi Thomas Bohl

The transverse impedance in the LHC is expected to be dominated by the numerous collimators, most of which are made of Fibre-Reinforced-Carbon to withstand the impacts of high intensity proton beams in case of failures, and which will be moved very close to the beam, with full gaps of few millimetres, in order to protect surrounding super-conducting equipments. We present an estimate of the transverse resistive-wall impedance of the LHC collimators, the total impedance in the LHC at injection and top energy, the induced coupled-bunch growth rates and tune shifts, and finally the result of the comparison of the theoretical predictions with measurements performed in 2004 and 2006 on a prototype collimator installed in the SPS.

Collimator

Resistive touchscreen

10.1109/pac.2007.4441125

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Citations (16)

Interim report for the International Muon Collider Collaboration (IMCC)

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) (2024)

C. Accettura Simon B. Adrian Rohit Agarwal C. Ahdida C. Aimè

Interim

Muon collider

10.23731/cyrm-2024-002

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Emittance sharing and exchange driven by linear betatron coupling in circular accelerators

Physical Review Special Topics - Accelerators and Beams (2007)

A. Franchi E. Métral Rogelio Tomás

The influence of linear betatron coupling due to constant-in-time skew quadrupolar fields on the transverse emittances is discussed using both a simplified model of a smooth circular accelerator and a more realistic strong-focusing lattice with localized sources of coupling (thin lens). New formulas for the coupled transverse emittances are derived that include the initial emittances, the coupling strengths, and the tune distance from the resonance. By using the more powerful Lie algebra and the resonance driving terms formalism, equivalent formulas are derived that provide a better understanding of some counterintuitive effects, otherwise not understandable in the smooth approximation. The new formulas have been tested both numerically and experimentally by using data of the CERN Proton Synchrotron showing a remarkable agreement.

Betatron

Proton Synchrotron

Coupling constant

10.1103/physrevstab.10.064003

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Citations (20)

Transverse Mode-Coupling Instability in the CERN SPS : Comparing Moses Analytical Calculations and Headtail Simulations with experiments in the SPS

Benoît Salvant R. M. Jones G. Rumolo Ralph Steinhagen Giulia Papotti

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Beam Induced RF Heating in LHC in 2015

7th International Particle Accelerator Conference (IPAC'16), Busan, Korea, May 8-13, 2016 (2016)

Benoît Salvant O. Aberle Markus Albert R. Alemany–Fernández G. Arduini

10.18429/jacow-ipac2016-mopor008

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MD 755: Instability threshold and tune shift study with reduced retraction between primary and secondary collimators in IR7

Lee Carver Benoît Salvant D. Nisbet Roderik Bruce Stefano Redaelli

Summary The purpose of this MD is to quantify in terms of stabilising octupole current threshold the impedance change when reducing the retraction between the primary and secondary collimators in IR7. This will be performed by rst measuring the octupole current threshold required for stability with the tighter secondary collimator settings at 6.5 (w.r.t. to the nominal settings at 8 ), and then measuring the tune shift that occurs when the collimators are moved to the new settings.

Collimator

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TRANSVERSE COHERENT INSTABILITIES IN THE PRESENCE OF LINEAR COUPLING

R. Cappi E. Métral D. Möhl

Strong coupling between the transverse planes of a particle beam leads to an “equipartition” of the oscillation energy, including the growth rates in the case of coherent instability. The aim of this paper is to give a general formula, which includes linear coupling and which extends to two dimensions the one-dimensional results of transverse coherent instabilities. From this equation, previous results are recovered as expected: (i) Sacherer’s formula for the coherent modes of oscillation, (ii) Kohaupt’s formula for the mode coupling instability, and (iii) the coupled Landau damping mechanism (transfer of frequency spread), which includes the sharing of the instability growth rates. Measurements have been performed in the CERN PS, which confirm the predicted beneficial effect of coupling by both frequency spread and chromaticity sharing.

Oscillation (cell signaling)

Equipartition theorem

Mode coupling

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Space charge and electron clouds issues

G. Franchetti G. Rumolo I. Hofmann M. Giovannozzi E. Shaposhnikova

We present here the relevant space charge issues for long-term beam storage. The impact on the choice of the working point along with the prediction of the beam loss is discussed for the example of the SIS100. We present a first estimate on the effect of self consistency and discuss the equivalence of space charge, and electron clouds induced ”quasi” incoherent effect.

10.5170/cern-2007-002.193

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Citations (1)