LANL, Los Alamos, New Mexico, USA
The Los Alamos Neutron Science Center (LANSCE) Risk Mitigation Project is in the process of replacing older Coupled-Cavity-Linac Beam-Position Monitors (BPMs) that in most locations include a separate Delta-T loop with newer Beam Position and Phase Monitors (BPPMs), including their associated electronics and cable plants. Twenty-three BPPMs have thus far been installed and many have monitored the charged particle beam. The installation of these newer BPPMs is the first step to installing complete BPPM measurement systems. Prior to the installation, a characterization of each BPPM took place. The characterization procedure includes a mechanical inspection, a vacuum testing, and associated electrical tests. The BPPM electrical tests for all four electrodes include contact resistance measurements, Time Domain Reflectometer (TDR) measurements, relative 201.25-MHz phase measurements, and finally a set of position-sensitive mapping measurements were performed which included associated fitting routines. This paper will show these data for a typical characterized BPPM.
LANL, Los Alamos, New Mexico, USA
The Los Alamos Neutron Science Center (LANSCE) deploys many cylindrical beam position and phase monitors (BPPM) throughout the linac to measure the beam central position, phase and bunched-beam current. Each monitor is calibrated and qualified prior to installation to insure it meets LANSCE requirements. The measurement system used to map the BPPMs electrode offset, sensitivity and higher order coefficients is the BPPM wire mapping system. This system uses a wire antenna structure to excite the interior of the BPPM at a fundamental frequency of 201.25 MHz, and as this field traverses the BPPM cavity, a three-axis motion table controls the antenna position. RF signal strength is measured and recorded on the four electrodes as the antenna position is updated. An effort is underway to extend the systems service to the LANSCE facility by replacing obsolete and antiquated hardware and taking advantage of software enhancements available since the 1990s. This paper will describe the updates to the wire positioning systems hardware and software capabilities including its unique antenna structure, motion control interface, RF measurement equipment and Labview software upgrades.