78 research outputs found
Magnetic stripping studies for SPL
No full textMagnetic stripping of H- can seriously enhance the beam losses along the SPL machine. These losses depend on the beam energy, on the beam transverse distribution and on the intensity of the magnetic field. For radioprotection issues the losses must be limited to 1 W/m. In this paper we will concentrate on the stripping phenomena inside the quadrupole magnets with the aim of defining the quadrupole range for the design phase of SPL
Choice of Linac parameters to minimize the space-charge effects
No full textInternational audienceIn high-intensity linear accelerators, the tune spreads induced by the space-charge forces in the radial and longitudinal planes are key parameters for halo formation and beam losses. For matched beams, they are the parameters governing the number of resonances (including coupling resonances), which affect the beam and determine the respective sizes of the stable and halo areas in phase space. The number and strength of the resonances excited in mismatched beams leading to even higher amplitude halos are also directly linked to the tune spreads. In this paper, the equations making the link between the basic linac parameters (rf frequency, zero-current phase advances, beam intensity and emittances) and the tune spreads are given. The analysis of the way these linac parameters can be chosen to minimize the tune spreads is presented. The ESS linac parameters are used as an example for this study
On the Choice of Linac Parameters for Minimal Beam Losses
No full textTUPWA034In high intensity linear accelerators, the tune spreads induced by the space-charge forces in the radial and longitudinal planes are key parameters for halo formation and beam losses. For matched beams they are the parameters governing the number of resonances (including coupling resonances) which affect the beam and determine the respective sizes of the stable and halo areas in phase space. The number and strength of the resonances excited in mismatched beams leading to even higher amplitude halos are also directly linked to the tune spreads. In this paper, the equations making the link between the basic linac parameters (rf frequency, zero-current phase advances, beam intensity and emittances) and the tune spreads are given. A first analysis of the way these linac parameters can be chosen to minimize the tune spreads is presented. The parameters of ESS linac are used for this study
On the Choice of Linac Parameters for Minimal Beam Losses
No full textTUPWA034In high intensity linear accelerators, the tune spreads induced by the space-charge forces in the radial and longitudinal planes are key parameters for halo formation and beam losses. For matched beams they are the parameters governing the number of resonances (including coupling resonances) which affect the beam and determine the respective sizes of the stable and halo areas in phase space. The number and strength of the resonances excited in mismatched beams leading to even higher amplitude halos are also directly linked to the tune spreads. In this paper, the equations making the link between the basic linac parameters (rf frequency, zero-current phase advances, beam intensity and emittances) and the tune spreads are given. A first analysis of the way these linac parameters can be chosen to minimize the tune spreads is presented. The parameters of ESS linac are used for this study
Alternative Options for the LINAC4 Transfer Line
No full textLINAC4 [1] is a 62mA, 160 MeV H- linac under study at CERN. LINAC4 should replace LINAC2, a 50 MeV proton linac, as injector to the PS booster. LINAC4 reference layout [2] foresees a transfer line, 193m long [3], which pass through the PS tunnel to join the present LT line at BHZ30. As an alternative layout we looked at the possibility of placing LINAC4 in place of LINAC2 and reusing the existing transfer lines. In addition we studied another line with new optics. The results of these investigations are reported in this paper
Doublet vs. FODO structure: beam dynamics and layout
No full textA FoDo (singlet) structure is designed for the CERN Superconducting Proton LINAC. This architecture is compared to the baseline (doublet) architecture of SPL on the basis of its beam dynamics performance and the required investment. The sensitivity of both layouts to quadrupole gradient errors and misalignment is checked and a correction scheme for beam steering is proposed. Finally a single quad beam dilution scheme is studied and designed for the pilot beam dump
Diagnostic Lines for the 160 MeV H Linac4 at CERN
No full textLinac4 will be the new linear accelerator of the CERN accelerator chain delivering H- ions at 160 MeV from 2016. The increased injection energy compared to the 50 MeV of its predecessor Linac2, combined with a H- charge-exchange injection, will pave the way to reach ultimate goals for the LHC luminosity. Extensive commissioning of Linac4 is planned for the coming years. For this purpose, the beam will be studied after the exit of Linac4 in a straight line ending at the Linac4 dump, equipped with various beam instruments. An almost 180 m long transfer line will guide the beam to the charge-exchange injection point at the entry of the Proton Synchrotron Booster (PSB). About 50 m upstream of this point, two measurement lines will be upgraded to perform transverse emittance measurements as well as energy and energy spread measurements of the Linac4 beam. A detailed description of the beam measurement principles and setups at these three Linac4 diagnostics lines related to distinct Linac4 commissioning phases will be given
Choice of the optimum beta for the SPL cavities
No full textThis note explains the reasoning behind the choice of the geometric betas for the superconducting cavities of the SPL
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