SEY AND CLEARING STUDIES AT KEKB

Studies on the structure of beam ducts, the inner surfaces with a low secondary electron yield (SEY) and clearing electrodes have been continuously progressing at the KEK B-factory (KEKB), in order to mitigate the electron cloud effect. Copper beam ducts with ante-chambers were installed in the positron ring. Test chambers with TiN and NEG coatings were also installed in the ring, and the effect of those on the electron cloud was investigated. A rod-type clearing electrode with low beam impedance was proposed, and the RF properties were preliminarily evaluated