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TY - UNPB AU - Tanaka, O. AU - Hotei, T. AU - Miyajima, T. AU - Nakamura, N. AU - Osaki, K. AU - Shimada, M. ED - Ramberger, Suitbert ED - Draper, Mick ED - Schaa, Volker RW TI - Beam Halo Study at the KEK Compact ERL J2 - Proc. of ERL2017, Geneva, Switzerland, June 18-23, 2017 C1 - Geneva, Switzerland T2 - ICFA Advanced Beam Dynamics Workshop T3 - 59 LA - english AB - The beam halo control is of a great importance to attain high intensity beams. Thus, its detailed treatment is indispensable for the stable and safe operation. A systematic beam halo study was established at the KEK Compact ERL (cERL) since machine commissioning in spring 2015 in order to understand the beam halo formation and to have the stable and safe operation. The results of halo simulations have given a reasonable explanation of the low bunch charge (0.2-0.3 pC) beam profiles evaluated during the measurement. Thus, vertical beam halos observed at cERL are supposed to be due to the longitudinal bunch tails transferred into the transverse plane. Tails are mainly produced by the cathode response on the laser excitation. Further, when a beam passing the rf cavity off-center it experiences rf field kicks. The beam tilt could be a complex effect of the steering coils and cavities misalignments. During spring 2017 commissioning the bunch charge was increased up to 40 pC. In present study we are challenging to describe how the space charge effect acts on the beam halo profiles, and how the halo formation mechanisms change in this connection. PB - JACoW Publishing CP - Geneva, Switzerland ER -