Beam Phase Lock Using Amplitude Limited Pulse Comparison for the Zero Gradient Synchrotron (ZGS)

Solid state high frequency limiter amplifiers and fast rise time voltage comparators for pulse shaping make zero crossing time a meaningful phase reference. A circuit based on these principles was developed and is in use in the beam phase feedback loop of the ZGS. It has excellent linearity for voltage out vs delay for up to 50° with a phase error of < 8° for the following input condition: input voltage amplitude from 0.1 - 2.0 V and beam bunch rate from 4.4 - 14.0 MHz. A detector is included to insure a zero output reference when there is no beam or when beam levels are below the phase-lock threshold.