Experimental beam tests for FCC-ee

Possible circular colliders for the post-LHC era at CERN are being explored within the framework of the Future Circular Collider (FCC) feasibility study. The first stage of the FCC integrated project is the FCC-ee, an ambitious electron-positron collider with a circumference of approximately 100 km. Certain key concepts of the FCC-ee design can be demonstrated and tested at existing facilities, such as at SuperKEKB at KEK, DA$\Phi$NE at INFN, KARA at KIT, PETRA III at DESY, VEPP-4M at BINP, and the SwissFEL at PSI. The test of a prototype positron source at PSI, understanding the crab-waist collision scheme at SuperKEKB and DA$\Phi$NE, testing optics control and emittance tuning techniques at SuperKEKB and PETRA III, and precise beam energy calibration at VEPP-4M will offer invaluable insights for the FCC-ee design optimization and its operational procedures. The results of these beam tests will be an essential input to the FCC Feasibility Study Report. This article will give an overview of possible experimental tests for FCC-ee and highlight already successfully performed studies.