Measurement of the Betatron Oscillation in a Phase Space near the Vertical Third-order Resonance

Abstract

We measured the betatron oscillation in a phase space near the vertical third-order resonance in the Photon Factory electron storage ring. In the measurement, the fast kicker magnets and the phase space monitor system were employed. Since the vertical resonance is non-structural one, it seemed that its strength was rather week. However, under a certain experimental condition, the stable resonance island was displayed on the phase space. In addition, we observed the island behavior with varying the octupole magnetic field strength. In this paper, we introduce the experimental method and result, and the discussion about the sources of the vertical third-order resonance.