A THERMOCOUPLE-BASED BEAM PROFILE MONITOR FOR AN 800 MEV PROTON ACCELERATOR

A thermocouple-based proton beam profile monitor is designed for use i n front of the Los Alamos Neutron Scattering Center target. The purpos e of the device is to determine the location and standard deviation of the incident proton beam using thermocouple temperatures. The beam pr ofile monitor consists of two perpendicular planes of thermocouple wir es mounted in 1 cm increments on Macor ceramic rings. Temperatures are measured from heat generated volumetrically in the thermocouple wires by the incident proton beam. Operating requirements for the device in clude the ability to work in pressure ranges of 0.1 to 10 Torr and at beam currents of 5 muA to 100 muA. Temperature data from a beam test a re compared with predictions from an analytical model, a finite elemen ts analysis using, the code TOPAZ2D, and an automated curve fitting ro utine. Average relative errors of less than 10% are calculated from th e analytical solution and the finite elements analysis. The curve fitt ing routine provides quick estimates of the proton beam parameters whi ch are useful during beam tuning.