Mini channel cooling systems have increasing trend of usage in various cooling applications such as computer microprocessors, air conditioning and refrigeration. Depending on the field of interest, geometry and material of mini channel cooling systems vary. On the other hand, mini channel configuration is in the promising direction of effective cooling for high heat load regions as in gyrotron resonance cavity. In this study, the thermal – hydraulic performance of copper mock-up of an ITER-like (International Thermonuclear Experimental Reactor) gyrotron cavity equipped with semi-circular straight mini channels subjected to inductive heating is studied. The commercial software STAR-CCM+ has been used to develop and simulate 3D – CFD (Computational Fluid Dynamics) model of the entire mock-up.