Beam phase stabilisation at the sin injector cyclotron

Abstract

A control system, designed to stabilize the phase of the extracted beam with respect to the Dee-voltage is described. Operating over the entire energy- and particle range of the SIN injector cyclotron, it requires no tuning over the rf frequency range of 4–17 MHz and at 51 MHz. Key components of the system are: A beam pick-up probe followed by wideband amplifiers with automatic gain control in the beam signal path, and a fast phase detector of high bandwidth, resolution and stability which features automatic gating for pulsed beam applications. The system's overall stability over a 2 h test period is better than 0.2° pp (rf, 51 MHz), with typical resolution at 0.01°, at beam currents above 1 μA at 72 MeVp (injector mode of the cyclotron).