M. Hourican

Injection and extraction magnets: septa

An accelerator has limited dynamic range: a chain of accelerators is required to reach high energy. A combination of septa and kicker magnets is frequently used to inject and extract beam from each stage. The kicker magnets typically produce rectangular field pulses with fast riseand/or falltimes, however the field strength is relatively low. To compensate for their relatively low field strength, the kicker magnets are generally combined with electromagnetic septa. The septa provide relatively strong field strength but are either DC or slow pulsed. This paper discusses injection and extraction systems with particular emphasis on the hardware required for the septa.

Direct Drive and Eddy Current Septa Magnet Designs for CERN's PSB Extraction at 2 GeV

In the framework of the LIU project, new septa magnets have been designed between CERNs PS booster (PSB) extraction and PS injection. The upgraded devices are to deal with the increased beam energy from 1.4 to 2 GeV at extraction of the PSB. The direct drive recombination septa in the PSB transfer line to the PS and the eddy current PS injection septum together with a bumper at injection have been investigated using finite-element software. For the recombination magnets, an increase in magnet length is sufficient to obtain the required deflection; however, for the PS injection elements, a more novel solution is necessary to also achieve increased robustness to extend the expected lifetime of the pulsed device. The injection septum will share the same vacuum vessel with an injection bumper, and both magnets will be located adjacent to each other. The new PS injection magnet will be the first septum operated at CERN based on eddy current technology. The magnetic modeling of the devices, the comparison of the performance of the present 1.4-GeV devices with the predictions for the upgraded 2-GeV devices, and the solutions retained to achieve the field requirements are described in this paper.

Design and Development of Separation Septa for the CERN PS Booster Upgrade

The CERN PS Booster project foresees the injection of 160 MeV H- ions into the booster from Linac 4. For this substantial upgrade, a system of 5 pulsed magnets (BIDIS) and 3 vertical septa (BISMV) will distribute the Linac pulses into the four-vertically separated Booster injection lines before being injected into the rings. This paper describes the magnetic calculations and the design concept that will be used in the future upgrade of the BISMV. Subsequently the mechanical design of the septa and their integration into the existing transfer line will be discussed.

Ions for LHC: Beam Physics and Engineering Challenges

The first phase of the heavy ion physics program at the LHC aims to provide lead-lead collisions at energies of 5.5 TeV per colliding nucleon pair and ion-ion luminosity of 1027cm-2s-1. The transformation of CERN’s ion injector complex (Linac3-LEIR-PS-SPS) presents a number of beam physics and engineering challenges, which are described in this paper. In the LHC itself, there are fundamental performance limitations due to various beam loss mechanisms. To study these without risk of damage there will be an initial period of operation with a reduced number of nominal intensity bunches. While reducing the work required to commission the LHC with ions in 2008, this will still enable early physics discoveries.