The Low-Level Control System for the CERN PS Multi-Turn Extraction Kickers

To reduce the beam losses when preparing high intensity proton beam for the CERN Neutrino to Gran Sasso (CNGS) facility, a new Multi-Turn extraction (MTE) scheme has been implemented in the PS, to replace the present Continuous Transfer (CT) to the SPS. Industrial off-the-shelf components have been used for the low-level part of the MTE kicker control system. National Instruments PXI systems are used to control the high voltage pulse generators and a SIEMENS programmable logic controller (PLC) handles the centralised oil cooling and gas insulation sub-system

Installation and Hardware commissioning of the Multi-Turn extraction at the CERN proton synchrotron

The implementation of the new Multi-Turn Extraction (MTE) at the CERN Proton Synchrotron required major hardware changes for the nearly 50-year old accelerator. The installation of new Pulse Forming Networks (PFN) and refurbished kicker magnets for the extraction, new sextupole and octupole magnets, new power converters, together with an in-depth review of the machine aperture leading to the design of new vacuum chambers was required. As a result, a heavy programme of interventions had to be scheduled during the winter shut-down 2007-8. The newly installed hardware and its commissioning is presented and discussed in details

The stripping foil test stand in the Linac4 transfer line

The 160 MeV H− beam from the Linac4 (L4) linear accelerator at CERN will be injected into the proton synchrotron booster (PSB) with a new H− charge-exchange injection system. It will include a stripping foil, to convert H− into protons by stripping off the electrons. To gain experience with these very fragile foils, prior to the installation in the PSB, and test different foil materials and thicknesses, lifetimes of the foils, the foil changing mechanism and interlocking functions, a stripping foil test stand will be installed in the L4 transfer line in 2015. This paper describes the mechanical design of the system and discusses the test possibilities and parameters

Cooling of the LHC Injection Kicker Magnet Ferrite Yoke: Measurements and Future Proposals

LHC operation with high intensity beam, stable for many hours, resulted in significant heating of the ferrite yoke of the LHC Injection Kicker Magnets. For one kicker magnet the ferrite yoke approached its Curie temperature. As a result of a long thermal time-constant the yoke can require several hours to cool sufficiently to allow re-injection of beam, thus limiting the running efficiency of the LHC. The beam screen, which screens the ferrite yoke from wakefields, has been upgraded to limit ferrite heating. In addition it is important to improve the cooling of the ferrite yoke: one method is to increase the internal emissivity of the cylindrical vacuum tank, in which the kicker magnet is installed. This paper describes a method developed for measuring the emissivity of the inside of the tanks, which has been benchmarked against measurements of the ferrite yoke temperature during heat treatment in an oven and transient thermal simulations. Conclusions are drawn regarding an ion bombardment technique evaluated for improving emissivity without degrading vacuum properties. In addition initial concepts for improved cooling are presented

Status of the 160 MeV H- Injection into the CERN PSB

The 160 MeV H- beam from the LINAC4 will be injected into the 4 superimposed rings of the PS Booster (PSB) with a new H- charge-exchange injection system. This entails a massive upgrade of the injection region. The hardware requirements and constraints, the performance specifications and the design of the H- injection region are described

Reduction of Surface Flashover of the Beam Screen of the LHC Injection Kickers

The LHC injection kicker magnets include beam screens to shield the ferrite yokes against wake fields resulting from the high intensity beam. The screening is provided by conductors lodged in the inner wall of a ceramic support tube. LHC operation with increasingly higher bunch intensity and short bunch lengths, requires improved ferrite screening. This will be implemented by additional conductors; however these must not compromise the good high-voltage behaviour of the kicker magnets. Extensive studies have been carried out to better satisfy the often conflicting requirements for low beam coupling impedance, fast magnetic field rise-time, ultra-high vacuum and good high voltage behaviour. A new design is proposed which significantly reduces the electric field associated with the screen conductors. Results of high voltage tests are also presented

Induced Activation in the Future Charge-Exchange Injection System of the PS Booster

CERN’s Linac2 currently injects protons with a kinetic energy of 50 MeV into the PS Booster (PSB). Linac2 will be replaced by Linac4 which will inject H$^-$ ions with a kinetic energy of 160 MeV into the PSB. In order to enable the PSB for charge-exchange injection, it will be equipped with a new injection system. The proposed charge-exchange injection system will use carbon foils (one for each of the four PSB rings) to remove the electrons from the H$^-$ ions. The remaining protons will then be merged with the already circulating proton beam. Two percent of the injected beam are expected to be either incompletely stripped or unstripped, and will be sent to 4 internal $\rm{H}^0/H^-$ injection dumps (one per PSB ring). This paper focuses on the induced activation in the future injection region. The radiological impact of proposed material choices for the internal dumps has been assessed by establishing Work and Dose Plannings for the most important foreseen interventions. The expected ambient dose equivalent rates at the various work locations have been obtained by FLUKA Monte Carlo simulations. In addition, the activation of the carbon foils and the derived need of protection measures during foil exchanges are discussed