IPAC2013 - List of Authors (Hernalsteens, C.)

Paper	Title	Page
WEPEA054	CERN PS Optical Properties Measured with Turn-by-turn Orbit Data	2627
	C. Hernalsteens, T. Bach, S.S. Gilardoni, M. Giovannozzi, A. Lachaize, G. Sterbini, R. Tomás, R. Wasef CERN, Geneva, Switzerland
	The performance of the PS has been constantly increasing over the years both in terms of beam parameters (intensity and brightness) and beam manipulations (transverse and longitudinal splitting). This implies a very good knowledge of the linear and non-linear model of the ring. In this paper we report on a detailed campaign of beam measurements based on turn-by-turn orbit data aimed at measuring the optics in several conditions as well as the resonance driving terms. The goal of this study is to assess whether any specific correction system should be envisaged to achieve the required future performance.

WEPEA055	Quantitative Evaluation of Trapping and Overall Efficiency for Simple Models in One-degree of Freedom	2630
	C. Hernalsteens, C. Frye, M. Giovannozzi CERN, Geneva, Switzerland A. Bazzani Bologna University, Bologna, Italy
	A key ingredient for the Multi-Turn Extraction at the CERN Proton Synchrotron is the beam trapping in stable islands of transverse phase space. The control of the trapping process is essential for the quality of the final beam in terms of intensity sharing and emittance. In this paper, a method allowing an analytical estimation of the fraction of beam trapped into stable islands as a function of the Hamiltonian parameters is presented for a very simple model of the dynamics (pendulum) and is extended to the case of the interpolating Hamiltonian of the Hénon model, the latter being a good 2D model of the MTE dynamics. The analytical results are compared with numerical simulations. Additional numerical simulations are presented for the minimum trapping amplitude and a fitted model is proposed. Results are discussed in detail.

WEPEA056	Design and Beam Measurements of Modified Fast Extraction Schemes in the CERN PS for Installing a Dummy Septum to Mitigate Ring Irradiation	2633
	C. Hernalsteens, H. Bartosik, L.N. Drøsdal, S.S. Gilardoni, M. Giovannozzi, A. Lachaize, Y. Papaphilippou, A. Ulsroed CERN, Geneva, Switzerland
	The proposed Multi-Turn Extraction (MTE) for the CERN PS allows to reduce the overall extraction losses for high intensity beams. The required longitudinal structure of the proton beam induces unavoidable beam losses at the magnetic extraction septum. The installation of a dummy septum with an appropriate shielding has been proposed to localise losses and to shadow the magnetic septum. Such a device, located in the extraction region, imposes tight constraints on the available beam aperture. Modified extraction schemes have been proposed and in this paper they will be presented and discussed in detail together with the measured performance.

WEPEA057	Numerical Simulations to Evaluate the Performance of CERN PS Dummy Septum to Reduce Irradiation for the Multi-Turn Extraction	2636
	C. Hernalsteens, S. Damjanovic, S.S. Gilardoni, M. Giovannozzi CERN, Geneva, Switzerland
	The losses created by the proposed Multi-Turn Extraction (MTE) at the CERN PS induces high activation of the magnetic extraction septum due to the de-bunched longitudinal beam structure requested to transfer the beam to the SPS. A mitigation measure is under study aiming at localizing losses in a well-shielded area by shadowing the magnetic extraction septum thanks to septum-like passive device. Such a solution is based on a so-called dummy septum, a blade which absorbs particles during the rise time of the extraction kickers for MTE beams. The efficiency of the scheme is presented in this paper. The quantitative estimate is based on detailed simulations that analyse the beam-matter interaction and provide a determination of the shadowing effect of the dummy septum.

WEPEA070	Space Charge Effects and Limitations in the Cern Proton Synchrotron	2669
	R. Wasef, G. Arduini, H. Damerau, S.S. Gilardoni, S. Hancock, C. Hernalsteens, A. Huschauer, F. Schmidt CERN, Geneva, Switzerland G. Franchetti GSI, Darmstadt, Germany
	Space charge produces a large incoherent tune-spread which, in presence of betatronic resonances, could lead to beam losses and emittance growth. In the CERN Proton Synchrotron, at the current injection kinetic energy (1.4 GeV) and even at the future kinetic energy (2 GeV), space charge is one of the main limitations for high brightness beams and especially for the future High-Luminosity LHC beams. Several detailed studies and measurements have been carried out to improve the understanding of space charge limitations to determine the maximum acceptable tune spread and identify the most important resonances causing losses and emittance growth.

Paper

Title

Page

CERN PS Optical Properties Measured with Turn-by-turn Orbit Data

2627

C. Hernalsteens, T. Bach, S.S. Gilardoni, M. Giovannozzi, A. Lachaize, G. Sterbini, R. Tomás, R. Wasef
CERN, Geneva, Switzerland

The performance of the PS has been constantly increasing over the years both in terms of beam parameters (intensity and brightness) and beam manipulations (transverse and longitudinal splitting). This implies a very good knowledge of the linear and non-linear model of the ring. In this paper we report on a detailed campaign of beam measurements based on turn-by-turn orbit data aimed at measuring the optics in several conditions as well as the resonance driving terms. The goal of this study is to assess whether any specific correction system should be envisaged to achieve the required future performance.

WEPEA055

Quantitative Evaluation of Trapping and Overall Efficiency for Simple Models in One-degree of Freedom

2630

C. Hernalsteens, C. Frye, M. Giovannozzi
CERN, Geneva, Switzerland
A. Bazzani
Bologna University, Bologna, Italy

A key ingredient for the Multi-Turn Extraction at the CERN Proton Synchrotron is the beam trapping in stable islands of transverse phase space. The control of the trapping process is essential for the quality of the final beam in terms of intensity sharing and emittance. In this paper, a method allowing an analytical estimation of the fraction of beam trapped into stable islands as a function of the Hamiltonian parameters is presented for a very simple model of the dynamics (pendulum) and is extended to the case of the interpolating Hamiltonian of the Hénon model, the latter being a good 2D model of the MTE dynamics. The analytical results are compared with numerical simulations. Additional numerical simulations are presented for the minimum trapping amplitude and a fitted model is proposed. Results are discussed in detail.

WEPEA056

Design and Beam Measurements of Modified Fast Extraction Schemes in the CERN PS for Installing a Dummy Septum to Mitigate Ring Irradiation

2633

C. Hernalsteens, H. Bartosik, L.N. Drøsdal, S.S. Gilardoni, M. Giovannozzi, A. Lachaize, Y. Papaphilippou, A. Ulsroed
CERN, Geneva, Switzerland

The proposed Multi-Turn Extraction (MTE) for the CERN PS allows to reduce the overall extraction losses for high intensity beams. The required longitudinal structure of the proton beam induces unavoidable beam losses at the magnetic extraction septum. The installation of a dummy septum with an appropriate shielding has been proposed to localise losses and to shadow the magnetic septum. Such a device, located in the extraction region, imposes tight constraints on the available beam aperture. Modified extraction schemes have been proposed and in this paper they will be presented and discussed in detail together with the measured performance.

WEPEA057

Numerical Simulations to Evaluate the Performance of CERN PS Dummy Septum to Reduce Irradiation for the Multi-Turn Extraction

2636

C. Hernalsteens, S. Damjanovic, S.S. Gilardoni, M. Giovannozzi
CERN, Geneva, Switzerland

The losses created by the proposed Multi-Turn Extraction (MTE) at the CERN PS induces high activation of the magnetic extraction septum due to the de-bunched longitudinal beam structure requested to transfer the beam to the SPS. A mitigation measure is under study aiming at localizing losses in a well-shielded area by shadowing the magnetic extraction septum thanks to septum-like passive device. Such a solution is based on a so-called dummy septum, a blade which absorbs particles during the rise time of the extraction kickers for MTE beams. The efficiency of the scheme is presented in this paper. The quantitative estimate is based on detailed simulations that analyse the beam-matter interaction and provide a determination of the shadowing effect of the dummy septum.

WEPEA070

Space Charge Effects and Limitations in the Cern Proton Synchrotron

2669

R. Wasef, G. Arduini, H. Damerau, S.S. Gilardoni, S. Hancock, C. Hernalsteens, A. Huschauer, F. Schmidt
CERN, Geneva, Switzerland
G. Franchetti
GSI, Darmstadt, Germany

Space charge produces a large incoherent tune-spread which, in presence of betatronic resonances, could lead to beam losses and emittance growth. In the CERN Proton Synchrotron, at the current injection kinetic energy (1.4 GeV) and even at the future kinetic energy (2 GeV), space charge is one of the main limitations for high brightness beams and especially for the future High-Luminosity LHC beams. Several detailed studies and measurements have been carried out to improve the understanding of space charge limitations to determine the maximum acceptable tune spread and identify the most important resonances causing losses and emittance growth.