Fabrication of Cylindrical Copper Waveguides with Sub-Millimeter Internal Rectangular Corrugations

There is great interest in having sources of short, intense pulses of Terahertz (THz) radiation to gain a better understanding, and ultimately to control, matter at the electronic, atomic, and molecular levels. This type of radiation source will be pertinent in fields as diverse as chemical and biological imaging, medical diagnostics and medical treatment, material science, telecommunications, semiconductor, and superconductor research. The next generation of THz frequency sources, as well as related instruments such as electron accelerators and wakefield accelerators, require new and improved components. Cylindrical copper waveguides, with internal corrugations, engineered to perform as slow-wave structures, are among the essential components needed. These metallic components will be used to generate and amplify THz frequency electromagnetic waves. To date, these components have only been produced in very limited quantities by end-users, by means of either extremely expensive X-ray LIGA facilities, or other approaches that lack the precision required for the intended applications. A much more cost-effective, high-precision alternative fabrication approach is required. We are proposing to use our well-established precision micromachining capability to produce sacrificial mandrels made out of fused silica glass. These exactingly-shaped mandrels will be electroplated with a thick layer of copper. Subsequent etching of the glass mandrel will result in the creation of cylindrical copper waveguides that have internal corrugations precisely engineered for the generation and amplification of THz frequency electromagnetic waves. In Phase I, we will design and fabricate waveguides with lengths up to 100-mm (4 inch). In Phase II, the fabrication hardware will be upgraded to produce waveguides with lengths up to 500-mm (20 inch) and we will test them in a relevant environment.