Design of EPICS based front-end feedback system for the EPU of SSRF

As the key components of modern light source, insertion devices affect performance directly of the light source. Due to technological limitations in manufacturing and installation of an insertion device, its magnetic field may well disturb the electron beam orbit. One solution to this problem is to add correction coils at both end of insertion device. A front-end feedback system, based on EPICS architecture, has been developed at SSRF for the elliptically polarized undulator (EPU10). It has been demonstrated that this feedback system has enhanced stability of beam current, with concise interface, complete functional control and real time control, hence the guaranteed higher quality of synchrotron radiations from the insertion devices, for the soft X-ray beam line and stations. (authors)