The LEDA beam-position measurement system

This paper describes the beam-position measurement system being developed for the Low Energy Demonstration Accelerator (LEDA) and the Accelerator Production of Tritium (APT) projects at Los Alamos National Laboratory. The system consists of a beam-position monitor (BPM) probe, cabling, down-converter module, position/intensity module, on-line error-correction system, and the necessary control system interfaces. The modules are built on the VXI-interface standard and are capable of duplex data transfer with the control system. Some of the key, system parameters are: position-measurement bandwidth of at least 180 kHz, the ability to measure beam intensity, a beam-position measurement accuracy of less than 1.25 percent of the bore radius, a beam-current dynamic range of 46 dB, a total system dynamic range in excess of 75 dB, and built-in on-line digital-system-error correction