Circular Corrugated Miter Bend and Gap Losses for Broadband Frequency Applications

Journal Article · Wed Nov 21 00:00:00 EST 2018 · IEEE Transactions on Microwave Theory and Techniques

DOI:https://doi.org/10.1109/TMTT.2018.2879808· OSTI ID:1493154

Lau, Cornwall H. ^[1]; Kaufman, Michael C. ^[1]; Doyle, E. J. ^[2]; Hanson, Gregory R. ^[3]; Peebles, W. A. ^[2]; Wang, Guiding ^[2]; Zolfaghari, Ali ^[4]

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1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2. Univ. of California, Los Angeles, CA (United States)
3. U.S. ITER Office, Oak Ridge, TN (United States)
4. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

Circular corrugated waveguides are often used in fusion applications at single, multiple, or broadband millimeter frequencies due to their low ohmic loss, expected large frequency bandwidth, and direct coupling to free-space Gaussian modes. For single-frequency corrugated waveguide systems, transmission line components can be optimized to the desired frequency. For broadband or multiple-frequency applications, this is not possible. The goal of this paper is to demonstrate that the frequency bandwidth of circular corrugated waveguides can be compromised by diffraction losses to miter bends and gaps. It is shown that if the corrugation depth differs significantly from λ /4, a theory can substantially underpredict the gap and miter bend losses. The simulations are also shown to compare favorably to experimental measurements. To improve the transmission line performance in large frequency bandwidth systems, such as 33–165 GHz reflectometry, reducing the number of miter bends may, therefore, be necessary. For the improvement of performance in narrower frequency bandwidth or multiple-frequency systems, especially high-powered systems, wavelength-dependent techniques may be applicable. Furthermore, one such application is shown for a Bragg reflection technique to reduce the thermal load to insulating ceramic rings in a dc break component for multiple-frequency ITER electron cyclotron heating transmission lines.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1493154
• Journal Information: IEEE Transactions on Microwave Theory and Techniques, Journal Name: IEEE Transactions on Microwave Theory and Techniques Journal Issue: 1 Vol. 67; ISSN 0018-9480
• Publisher: IEEE
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
corrugated waveguide
full-wave simulation
gap
miter bend
waveguide theory