Space charge effects during the injection period of the KEK PS main ring

Space charge effects during the injection period of the 12 GeV main ring of the KEK proton synchrotron have been studied. Measurement of the transverse beam profiles using flying wires has revealed a characteristic temporal change of the beam profile within a few milliseconds after injection. Horizontal emittance growth was observed when the horizontal tune was close to the integer. The effect was more enhanced for higher beam intensity and could not be explained with the injection mismatch. Resonance created by the space charge field was the cause of the emittance growth. A multiparticle tracking simulation program, ACCSIM, taking account of space charge effects has qualitatively reproduced the beam profiles.