Status of the High Energy Booster of the lepton option of the future circular collider

In the context of the FCC IS European study, which investigates the feasibility of a 100 km circular 𝑒+𝑒− collider for the future high-energy physics research, we present the status of the High Energy Booster (HEB) ring. In order to perform precision measurements of the Z, W and H bosons, as well as of the top quark, unprecedented luminosities are required. To reach this goal and to fill the collider, it is mandatory to continuously top up inject some beams with a comparable emittance to the collider ones and a bunch-by-bunch intensity variation below few %. The main challenges of the HEB are the fast cycling time to reach the collider equilibrium emittances and the minimum injection energy into the booster that allows a stable operation. We present the status of the optics design of the HEB taking into account these challenges, and the impact of magnetic field imperfections on the dynamic aperture at injection.