Assembly and preliminary testing of the prototype 650 GHz BWO

Approximately twenty intricate diamond structures have been fabricated, selectively metallized and assembled into prototype 650 GHz backward wave oscillators (BWOs). The chemical vapor deposition (CVD) diamond structure is grown into a silicon mold fabricated using deep reactive ion etching. The lithographic fabrication processes employed produce dozens of devices from each lot. The RF power generated is radiated directly from the BWO for compatibility with a quasi-optical sub-mm system. The interdigital slow wave circuit, the electron gun, the output coupler and the antenna are fabricated as a single piece of diamond to eliminate difficulties with alignment. We will describe the processes of fabrication and assembly, and present available preliminary results of prototype testing.