Horizontal Correctors (Steerers)

The most effective correction is obtained when the correctors are located as near as possible to the sources of generating the largest orbit deviations, i.e. the quadrupoles. There are a total of 191 horizontal corrector magnets in use for slow orbit correction in PETRA III storage ring. The alternate dipole magnet in the old octant has a backleg winding to be used as a corrector magnet. They are 112 in number (PKDK). In the short and long straight sections the horizontal corrector magnets are iron core water cooled magnets. They are placed near to high b_x points at focusing quadrupoles. In total they are 61 (Hera type 24(PCH, 0.3m), BINP type 12(PKHW, 0.106m), and New 25(PKH, 0.2m)) in number including the new DBA section. Unlike the old octants new octant all dipoles will have a correction winding too. They are 18 in number (PKDPA). According to the accuracy of power supply settings required to obtain beam orbit stability in horizontal plane, the steering magnets setting resolution is ³16 bit.

For estimation of maximum horizontal corrector strength, 200 random corrections are made and the maximum corrector strengths are saved.  It shows that a maximum of 0.5mrad is sufficient to carry out the slow orbit correction scheme for PETRA III. The results are reproduced below.

Form the maximum strength of 0.5mrad, the integrated magnetic field required to get such a kick at 6GeV is 100 G.m.

q_max » 0.5mrad Þ Bl= 100G.m

The horizontal correctors are classified to 4 categories according to its position and function. The backleg winding in dipoles are named as PKDIP (PKDIP.SWR.027 to PKDIP.SWL.027), the independent slow correctors are named as PCH (PCH.SWR.009 to PCH.SWL.009) in the old octant brought from HERA ring, PKH (PKH.NOR.040 to PKH.OL.064) in the new octant, PKHW (PKHW.WL.031 to PKHW.NR.030) in the damping wiggler sections and fast corrector magnets are named as PKHSA (PKHSA.WL.032 to PKHSA.SWL.007 of length 0.4m) in the long straight sections of old octant as well as PKHS (PKHS.NOR.041 to PKHS.OL.063 of length 0.2m) in the new octant.

Phase advances among the Horizontal Correctors:

Home page of Orbit Movement and Beam Position Control