SYSTEM OVERVIEW AND DESIGN CONSIDERATIONS OF THE BPM SYSTEM OF THE ESS LINAC

Abstract The ESS Linac will include in total more than 140 Beam Position Monitors of different sizes and types. The BPM system needs to measure the beam position, phase and intensity in all foreseen beam modes with a pulse rate of 14 Hz, duration of 2.86 ms and amplitude ranging form 5 mA to 62.5 mA. With respect to the BPM connection to the Machine Interlock System, the total response time must be less than 10 s. The signal level variations from one BPM to another along the Linac should be as small as possible to meet the requirements on the analog gain of the front-end electronics and the dynamic range of the digitizer card input. The other requirement is that the BPM system needs to give at least a rough estimation of the beam position and phase, even if the beam is significantly debouched, ex. during the Linac tuning phase. These requirements and their impact on the design of the BPM detector, the analog front-end electronics and the selection of the digitizer card are discussed in this paper along with a general description of the BPM system

Machine Protection Features of the ESS Beam Current Monitor System

The BCM system of the European Spallation Source includes several machine protection features to ensure that the actual beam parameters will be consistent with the selected beam and destination modes. Differential current measurements with several ACCT pairs are foreseen to detect beam losses particularly in the low energy linac where Beam Loss Monitors cannot be used.The ACCTs will also be used to check that no beam will be present in the sections downstream of a temporary beam dump. These measurements will then be used to stop the beam shortly after an abnormal condition has been detected by the BCM system. This will require some customized interfaces with the Timing System and the Machine Protection System as well as an optical interface for differential current measurement over large distances. Automatic setting of the machine protection thresholds and masking/unmasking of the interlocks based on the beam and destination modes are among the technical complexities. This paper gives an overview of the design including the most recent updates and discusses in more details the machine protection features of the BCM system

ESS Beam Position and Phase Monitor System

The European Spallation Source (ESS) is a neutron facility under construction in Lund, Sweden, and established as a European collaboration between different member countries. The machine is a 2 GeV proton LINAC with a nominal beam current of 62.5 mA, 2.86 ms of pulselength and a bunch repetition rate of 352 MHz. The Beam Position and Phase Monitors (BPM) at ESS were designed to satisfy the specifications for the different beam modes,which span from 5 μs pulse length and 6.3 mA beam untilthe nominal beam condition. The system is designed for standard beam position measurements for beam trajectory correction and for beam phase measurements for cavity phase tuning, imposing restrictions on the sensor design and electronics architecture. Approximately a hundred BPM's were manufactured and are being installed by partners in collaboration with ESS. The BPM system comprises a MicroTCA.4 electronics based in COTS AMCand RTM modules with custom FPGA firmware implementation and a custom Front-End electronics. In this work, the system architecture, implementation, and test results are presented and discussed

Overview and status of diagnostics for the ESS project

The European Spallation Source, now under construction in Lund, Sweden, aims to be the world's most powerful pulsed neutron scattering facility. Driving the neutron source is a 5 MW superconducting proton linear accelerator operating at 4 percent beam duty factor and 14 Hz repetition rate. Nineteen partner institutions from across Europe are working with the Accelerator Division in Lund to design and construct the accelerator. The suite of accelerator instrumentation consists of over 20 unique system types developed by over 20 partners and collaborators. Although the organizational complexity presents challenges, it also provides the vast capabilities required to achieve the technical goals. At this time, the beam instrumentation team is in transition, completing the design phase while scaling up to the deployment phase. Commissioning of the ion source has commenced in Catania, preparations for installation on the Lund site are ramping up, and basic R&D on target instrumentation continues. Beam commissioning results from the systems immediately following the ion source will be presented, along with technical highlights and status of the many remaining instrumentation systems

Status of the RAL Front End Test Stand

The Front End Test Stand (FETS) under construction at the Rutherford Appleton Laboratory is the UK's contribution to research into the next generation of High Power Proton Accelerators (HPPAs). HPPAs are an essential part of any future Spallation Neutron Source, Neutrino Factory, Muon Collider, Accelerator Driven Sub-critical System, Waste Transmuter etc. FETS will demonstrate a high quality, high intensity, chopped Hminus beam and is a collaboration between RAL, Imperial College and the Universtity of Warwick in the UK and the Universidad del Pais Vasco and ESS-Bilbao in Spain. This paper describes the current status and future plans of FETS