  The upgrade project of Hefei Light Source storage ring is under way. In this
paper, the broadband impedances of resistive wall and coated ceramic vacuum
chamber were calculated using the analytic formula, the wake fields and
impedances of other designed vacuum chambers have been simulated by the CST
code, and then the broadband impedances model was obtained. Using the
theoretical formula, longitudinal and transverse single bunch instabilities
were discussed. With the carefully-designed vacuum chamber, we find that the
thresholds of the beam instabilities are higher than the beam current goal.
