Beam stabilization at LNS Linac

The 300 MeV electron Linac at the Laboratory of Nuclear Science, Tohoku University is also used for stretcher booster ring radiation injector. When operating this ring at a stretcher mode, it has been found that pulse beam from Linac changes periodically in each six pulses. As this change has six colors' in the beam, it has been called 'six color problem'. This six color problem is thought to be a large obstacle to clear a design value such as peripheral current amount and so forth on operation of the stretcher booster ring at present. In order to solve this problem, to lay beam current and so forth to a design value, and to make beam stabler, this study was carried out. As a result, it was found that RF output in klystron changed at the same phase with this change. Then, it was thought that this changed mainly caused at instability in RF output in klystron. (G.K.)