A thermocouple-based beam profile monitor for an 800 MeV proton accelerator

A thermocouple-based proton beam profile monitor is designed for use in front of the Los Alamos Neutron Scattering Center target. The purpose of the device is to determine the location and standard deviation of the incident proton beam using thermocouple temperatures. The beam profile monitor consists of two perpendicular planes of thermocouple wires 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 include the ability to work in pressure ranges of 0.1 to 10 Torr and at beam currents of 5 μA to 100 μA. Temperature data from a beam test are compared with predictions from an analytical model, a finite elements analysis using the code TOPAZ2D, and an automated curve fitting routine. Average relative errors of less than 10% are calculated from the analytical solution and the finite elements analysis. The curve fitting routine provides quick estimates of the proton beam parameters which are useful during beam tuning. (orig.)