A NON-DESTRUCTIVE PROFILE MONITOR FOR HIGH INTENSITY BEAMS

A non-destructive profile monitor has been installed and commissioned in the accumulator ring of Spallation Neutron Source (SNS). The SNS Ring accumulates during a 1 ms cycle high intensity proton bunches of up to 1.5e14 protons with a typical peak current of over 50 A and a bunch length of about 0.7 μs. The profile monitor consists of two systems, one for each plane, with electron guns, correctors, deflectors, and quadrupole magnets to produce pulsed electron beams that scan through the proton bunch. The electric and magnetic fields of the proton bunch alter the trajectory of the electrons and their projection on a fluorescent screen. The projection is analyzed to determine the transverse profile of the proton bunch. Because the duration of the electron scan is very short compared to the bunch length, the longitudinal profile can be obtained by making multiple scans while varying the time delay relative to the proton bunch. This paper describes the theory, the hardware and software, analysis, and results of, as well as improvements made to the electron scanners. The results include a comparison of wire scanner profiles of extracted ring beam with the profiles of ring beam from the electron scanner.