Phase and synchronous detector theory as applied to beam position and intensity measurements
A popular signal processing technique for beam position measurements uses the principle of amplitude-modulation-to-phase-modulation (AM/PM) conversion and phase detection. This technique processes position-sensitive beam-image-current probe-signals into output signals that are proportional to the beam's position. These same probe signals may be summed and processed in a different fashion to provide output signals that are proportional to the peak beam current. This paper derives the transfer functions for the AM/PM beam position and peak beam current processors.
Comparison of beam-position-transfer functions using circular beam-position monitors
A cylindrical beam-position monitor (BPM) used in many accelerator facilities has four electrodes on which beam-image currents induce bunched-beam signals. These probe-electrode signals are geometrically configured to provide beam-position information about two orthogonal axes. An electronic processor performs a mathematical transfer function (TF) on these BPM-electrode signals to produce output signals whose time-varying amplitude is proportional to the beam's vertical and horizontal position. This paper compares various beam-position TFs using both pencil beams and further discuss how diffuse beams interact with some of these TFs.
A Magnetic Beam Position Monitor
We give the theory and describe the execution of the magnetic beam position monitors in use in the AGS injection line. These are strictly linear devices of very low impedance with a rise time of the order of 1 ?sec. They do not require electronics close to the device and have been constructed to withstand considerable radiation. Their construction is simple and not critical.