Simulation Study of the Electron Cloud Instability in SuperKEKB

A simulation of a build-up of an electron cloud in SuperKEKB was done by a program CLOUDLAND. Average electron density and electron density at the center of a vacuum chamber were calculated in a drift space and in various magnetic fields. The result shows that a solenoid field is very effective in reducing the electron density and the simulated electron density is below the threshold electron density of the strong head-tail instability by the electron cloud if solenoids are installed in the drift space.