Suppression of beam instability in the electron storage ring of HLS

During the commission of electron storage ring of HLS(phase Ⅱ reconstruction), it was found that there was coupled-bunch instability both in injection and operation. The coupled-bunch instability seriously limited the injection beam intensity, and affected the stabilization of operation of Hefei light source. By using over compensated chromaticity and insertion octupole magnet in storage ring, the transverse coupled-bunch instability was almost suppressed, and the design goal of storing 300 mA was achieved.