High power miter-bend for the Next Linear Collider

In the design of the Next Linear Collider (NLC), it may be necessary to transmit very high power levels (hundreds of megawatts) of microwave radiation over distances of tens of meters. The microwave transmission system will require the use of oversized waveguides and higher order modes in order to either avoid breakdown or to optimize the microwave system properties. We have studied one critical component of the proposed waveguide transmission system, namely a miter-bend for the TE₀₁ mode capable of transmitting over 600 MW of power at 11.424 GHz. The miter-bend is a quasi-optical 90-degree bend. The design is based on previous, successful designs of miter-bends for high average power gyrotrons at frequencies of 35 GHz and above. The design consists of a profiled mirror and two oversized rippled-wall mode converters optimized to provide less than 0.1 dB operating mode losses