In this article, RF behavior studies on a W-band continuous wave (CW) gyrotron for industrial, scientific, and medical applications are presented. Two different designs are carried out for the output power level of 50 and 100 kW. The mode competition with the first and second harmonic neighboring modes is carefully investigated, and TE6,2 and TE10,4 are Chosen as the operating modes for these designs. The cold cavity design and self-consistent computations for power and efficiency are done to determine the geometrical and beam parameters of the desired modes using the in-house code, Gyrotron Design Suite Second Harmonic Version 2018 (GDS2H-V. 2018). The desired output power is obtained for two different designs at the Chosen cavity modes. Additionally, electron guns along with magnetic guidance systems are designed to generate an electron beam with the required beam parameters for the two designs.