Advanced simulation tools were used to design major components for a 95-GHz traveling-wave tube (TWT) providing approximately 1-kW of average power. This output power would be challenging, if not impossible, using a fundamental mode circuit TWT design, because of beam-current density and thermal-mechanical-stability issues. We addressed these limitations using an overmoded interaction circuit. The program investigated the circuits' thermal and electrical performance, including the effect of multiple-propagating modes and spurious oscillations. We also completed the designs for the electron gun and periodic permanent magnet. The design results for the 1-kW 95-GHz TWT are promising.