Simulation Analysis of Head-Tail Motion Caused by Electron Cloud

Synchro-beta side band signal caused by electron cloud instability has been observed at KEK-B factory. The side-band appears above the threshold of beam size blow-up and disappears by exciting solenoid magnets which covers whole ring. The side-band is an evidence of strong head-tail instability caused by electron cloud. The side-band appears in tune spectrum with positive shift νβ+ aνs(1 < a < 2), while general strong head-tail instability shows a negative shift νβ− aνs(a > 0). We study the synchro-beta spectrum using a code, PEHTS, which simulates single bunch electron cloud instability.