Characterizing Supersonic Gas Jet-based Beam Profile Monitors

The next generation of high power, high intensity accelerators requires non-invasive diagnostics, particularly beam profile monitors. Residual gas-based diagnostics such as ionization beam profile or beam induced fluorescence monitors have been used to replace commonly used scintillating screens. At the Cockcroft Institute an alternative technique using a supersonic gas jet, shaped into a 45o curtain screen, was developed. It has already demonstrated its superior performance in terms of resolution and signal-to-noise ratio in comparison with residual gas monitors in experimental studies. The performance of this type of monitor depends on the achievable jet homogeneity and quality. Using a movable vacuum gauge as a scanner, the dynamic characteristics of the jet are studied. In this paper we also give an analysis of the resolution for this monitor in detail from the theory and ion drift simulation.