Abstract The uniformity and quality of diamond films deposited in Microwave Plasma Chemical Vapor Deposition (MPCVD) reactors are significantly challenged by non-uniform plasma distributions and low growth rates. This study combines multi-physics numerical simulations with experimental investigations to optimize diamond deposition in a home-built cylindrical resonant-mode MPCVD reactor. A comprehensive multi-physics model coupling electromagnetic fields, fluid dynamics, and hydrogen-methane plas