A Longitudinal Phase Space Monitor at the Photon Factory Storage Ring

A phase detection circuit was developed to observe a synchrotron oscillation of the beam turn-by-turn at the Photon Factory Storage Ring (PF ring). A phase deviation from RF frequency was measured using the circuit connected to one of the button-type electrodes of the beam position monitor (BPM). A momentum deviation of the beam was simultaneously measured using a transverse beam position circuit of BPM placed on the dispersion section of the ring. These circuits were controlled with the on-line computer through GP-IB interface. Experimental data were taken in a stored single-bunch beam at a current of 10 mA. The resolution and the dynamic range of the phase detection circuit were less than 0.136 deg and over 8 deg, respectively. Then the tracking of the large coherent synchrotron oscillation caused by an RF phase modulation and a longitudinal single-bunch instability was displayed with a good accuracy on the longitudinal phase space.