Polarized electron beams in the MEIC Collider ring at JLab

The nuclear physics program of the Medium-energy Electron-Ion Collider (MEIC) at the JLab requires a highly-polarized (over 70%) electron beam with longitudinal polarization at the collision points. This can be achieved by arranging the equilibrium polarization direction to be vertical in the arcs of the figure-8 shape ring and longitudinal at collision points. The rotation of the polarization is accomplished at each energy by using universal spin rotators, each of which consists of a set of solenoids and dipoles placed at the end of each arc. To reduce the spin-orbit depolarization effect due to the synchrotron radiation, spin matching to make the sections between the rotators in the long straights spin transparent has to be considered. We present the current universal spin rotator design, address various coupling compensation schemes for the solenoids, provide polarization configurations based on the spin rotators' layout, and briefly explore the use of continuous injection of electrons from the CEBAF into the MEIC collider ring for maintaining high equilibrium polarization. This continuous injection might be less demanding than spin matching.