Beam property management at KEK electron/positron 7-GeV injector

The electron/positron injector linac at KEK has injected a variety of beams into the electron accelerator complex of SuperKEKB collider and light sources for particle physics and photon science experiments for more than 30 years. The beam property of electrons and positrons varies in energy from 2.5 GeV to 7 GeV and in bunch charge from 0.2 nC to 10 nC, and their stability requirements are different depending on the injected storage rings. They have to be switched by pulse-to-pulse modulation at 50 Hz. The emittance control is especially crucial to achieve the goal at SuperKEKB and is under development. The beam energy management becomes more important as it affects all of the beam properties. Beam acceleration provided by 60 high-power microwave stations should be properly distributed considering redundancy and stability. Thus, the equipment controls are also restructured in order to enable the precise control of the beam properties, based on the synchronized event control system and EPICS control system. The strategy and status of the upgrade is described in this paper from the practical aspects of device controls, online simulation and operation. (author)