  In the Rapid Cycling Synchrotron(RCS) of China Spallation Neutron
Source(CSNS), transverse painting injection is employed to suppress the
space-charge effects. The beta-beating caused by edge focusing of the injection
bump magnets leads to tune shift and shrinkage of the acceptance, which may
result in additional beam loss. In RCS, the main quadrupoles are excited by
White resonant power supplies, and the exciting current cannot be arbitrarily
programed. Generally, this kind of perturbation could be corrected by
trim-quadrupole, however, we don't have trim-quadrupole in CSNS/RCS. A new
method based on the harmonic injection is firstly introduced to compensate the
beta-beating caused by edge focusing of the chicane bump magnets at RCS. In
this paper, the principle and feasibility of compensation scheme were
presented. The simulation study was done on the application of the new method
to the CSNS/RCS, and the results show the validity and effectiveness of the
method.
