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TY - CONF AU - Suetsugu, Y. AU - Fukuma, H. AU - Hisamatsu, H. AU - Ikeda, H. AU - Ishibashi, T. AU - Kanazawa, K. AU - Lee, Y.M. AU - Ohmi, K. AU - Shibata, K. AU - Shirai, M. AU - Terui, S. AU - Tobiyama, M. ED - Biagini, Maria Enrica ED - Chrin, Jan ED - Giabbai, Manuela ED - Iungo, Massimiliano ED - Schaa, Volker R.W. TI - Mitigation of Electron Cloud Effect in the SuperKEKB Positron Ring J2 - Proc. of eeFACT2022, Frascati, Italy, 12-16 September 2022 CY - Frascati, Italy T2 - ICFA Advanced Beam Dynamics Workshop on High Luminosity Circular e+e- Colliders T3 - 65 LA - english AB - One critical issue for the SuperKEKB is the electron cloud effect (ECE) in the positron ring, and various countermeasures had been prepared before starting the commissioning. The ECE, however, was observed during phase-1 commissioning (2016) caused by the electron cloud in the beam pipes at drift spaces of the ring, which had antechambers and a TiN-film coating. Permanent magnets and solenoids to generate magnetic fields in the beam direction were attached to the beam pipes as additional countermeasures before the next phase-2 commissioning (2018). Consequently, the threshold of the current linear density for exciting the ECE increased by a factor of at least 2. During Phase-3 commissioning (2019), it was confirmed that the threshold was over 0.53 mA/bunch/RF bucket, and we have observed no clear evidence of ECE in the usual operation up to now. The effectiveness of the ante-chambers and TiN film coating of the real beam pipe was reevaluated. The present ante-chambers were found to be less effective than expected with regard to reducing the number of photoelectrons in the beam channel. Here we will summarize the mitigation techniques used in the SuperKEKB and the results so far. PB - JACoW Publishing CP - Geneva, Switzerland SP - 146 EP - 153 KW - electron KW - MMI KW - solenoid KW - experiment KW - simulation DA - 2022/02 PY - 2022 SN - 2673-7027 SN - 978-3-95450-236-3 DO - doi:10.18429/JACoW-eeFACT2022-WEYAT0102 UR - https://jacow.org/eefact2022/papers/weyat0102.pdf ER -