High power miter-bend for the Next Linear Collider

Abstract

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 TE 01 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.

QUASI-OPTIC BASED HE₁₁ MITER BEND AT 42 GHZ FOR ECRH APPLICATION

“…The miter bend is a critical component of TL that contributes to a loss value more than 80% in a total loss. The majority of miter bends have been designed at lower modes like TE 01 mode [10] for circular waveguide and HE 11 mode for overmoded corrugated waveguide [11][12][13]. Out of the two miter bends, the design and fabrication of HE 11 miter bend are more challenging and costly, hence require more precaution.…”