160 MeV H- injection into the CERN PSB
The H- beam from the proposed LINAC4 will be injected into the four existing rings of the PS Booster at 160 MeV. A substantial upgrade of the injection region is required, including the modification of the beam distribution system and the construction of a new H- injection system. This paper discusses beam dynamics and hardware requirements and presents the results of optimisation studies of the injection process for different beam characteristics and scenarios. The resulting conceptual design of the injection region is presented, together with the main hardware modifications and performance specifications.
PIMS—A simple and robust accelerating structure for high intensity proton Linacs
Abstract A π -mode structure (PIMS) is investigated for an application in a high duty cycle, high intensity proton Linac. Motivated by the objective to employ a simple and robust accelerating structure at a resonance frequency of 352 MHz for the high energy part of Linac4 (100–160 MeV), the normal conducting LEP cavity is restudied and its design is adopted for a medium β ( β ≈ 0.5 ) application. The geometry of the accelerating cell is optimised, the necessary cell-to-cell coupling coefficient is analysed and a novel solution for the shape of the coupling slots is discussed. Simulation results are compared to measurement results obtained from three 3-cell cold models and one 7-cell cold model. The method of tuning the resonance frequency of individual cells is presented and the tuning of end cells is explained in detail. An adjustable wave guide coupler is used to power the cavities, and we present the design process for this device. The behaviour of the PIMS to dynamical changes—as observed during the filling process of the cavity and under beamloading with a chopped beam—as well as the effect of thermal drifts are evaluated.
Status of the LEP accelerating structure
The LEP (Large Electron Positron colliding beam accelerator) uses a dual-frequency acceleration system consisting of coupled accelerating and storage cavities. Basic design features of this system with its accessories and tuning system are described. One hundred and thirty cavities have been built by industry; the assembly and conditioning with RF power were done at CERN. All cavities are now installed in the LEP tunnel. The procedures used and first experiences are presented.<<ETX>>