Emittance mismatching of electron injection for the Electron Storage Ring of the Electron-Ion Collider

The Electron-Ion Collider (EIC), to be constructed at Brookhaven National Laboratory, will collide polarized high-energy electron beams with polarized proton and ion beams, achieving luminosities of up to 1 × 10³4 cm^−2 s^−1 in the center-of-mass energy range of 20-140 GeV. The EIC consists of two storage rings: the Hadron Storage Ring (HSR) and the Electron Storage Ring (ESR). Given the short polarization lifetime of the electrons, a swap-out injection scheme is adopted for the ESR injection. In this article, we estimate the injection mismatch tolerances for the electron swap-out injection from the Rapid Cycling Synchrotron to the ESR. In these studies, strong-strong beam-beam simulations are performed. The tolerances for injection emittance mismatch in the ESR are presented in this article.