CERN, Geneva
ESS, Lund
SPL is a superconducting H- LINAC under study at CERN. The SPL is designed to accelerate the 160 MeV beam of LINAC4 to 4-5 GeV, and is composed of two families of 704.4 MHz elliptical cavities with geometrical betas of 0.65 and 1.0 respectively. Two families of cryo-modules are considered: the low-beta cryo-module houses 6 low-beta cavities and 4 quadrupoles, whereas the high-beta one houses 8 cavities and 2 quadrupoles. The regular focusing structure of the machine is interrupted at the transition between low beta and high beta structure and at 1.4 and 2.5 GeV for extracting medium energy beam. The accelerator is designed for max. 60 mA peak current (40 mA average) and max. 4% duty cycle, implying a very accurate control of beam losses. In particular the choice of the diagnostics and correction system, the maximum quadrupole gradient to avoid Lorentz stripping and the effect of the RF power delivery system on the beam quality are discussed in this paper.
CERN, Geneva
Linac4 is a 160 MeV H- ions accelerator, which will replace the 50 MeV proton Linac (Linac2) as injector for the CERN complex from 2015. The higher output energy together with charge-exchange injection will allow increasing beam intensity in the following machines. Linac4 is about 100m long, normal-conducting, and will be housed in a tunnel, 12m below ground, on the CERN Meyrin site. The low energy front-end, consisting of a 45 KeV source, a 3-m long RFQ and a 3 MeV chopper line, will be commissioned starting next year in a temporary location. It will then be moved to the tunnel at the end of 2012 and the commissioning in situ will be done progressively with the installation of the accelerating structures. The preparation of 4 commissioning stages (12, 50 100, and 160 MeV) is of key importance to meet the goals of beam performance and reliability. An extensive campaign of simulation is in progress to define the necessary measurements and the required diagnostics accuracy for a successful set-up of the transverse and longitudinal parameters of the machine. This paper presents the results of the simulations and the measurement strategy.