The Design and Performance of the Integrated Spallation Neutron Source Vacuum Control System

The Spallation Neutron Source (SNS) vacuum control systems have been developed within a collaboration of Lawrence Berkeley National Laboratory (LBNL), Los Alamos National Laboratory (LANL), Thomas Jefferson National Accelerator Facility (TJNAF), and Brookhaven National Laboratory (BNL). Each participating lab is responsible for a different section of the machine: LBNL for the Front-End section, LANL for the warm LINAC section, TJNAF for the cold LINAC section and BNL for the Ring section. Although a great deal of effort has been made to standardize vacuum instrumentation, components and global control system interfaces, the varied requirements of the different sections of the machine have made horizontal integration of the individual vacuum control systems both interesting and challenging. To support machine commissioning, the SNS control and vacuum teams have developed and implemented a series of test strategies and interlock schemes that have allowed horizontal vacuum system integration to be achieved in an effective manner. The design of the vacuum control system interlock schemes developed will be discussed together with the results of performance measurements made and experience gained in developing real-time control with an industrial Ethernet for this application.

INTRODUCTION

The success of the SNS is measured by the high availability of all systems during operation including vacuum subsystems and their components. Beam energy increases as it progress through from the ion source to final delivery of the beam on the target with vacuum operating levels varying to support physics requirements. (see table 1) [1]. The design of the SNS vacuum system and its control system has been achieved through a multi-laboratory collaboration. To maintain the necessary high reliability, availability and flexibility of the vacuum system, both Programmable Logic Controllers (PLCs) and EPICS Input and Output Controllers (IOCs) are used for controlling and monitoring the vacuum devices except for the superconducting vacuum control system that required a fast response time for the sector gate valves (SGVs) [6]. Although a great deal of effort has been taken to standardize vacuum instrumentation, components and global control system interfaces [2], two major challenges had to be overcome for the successful integration of the individual vacuum control systems delivered by different partner labs.