Circular waveguide mode converters at 140 GHz
A unified derivation of the coupled mode equations for circular waveguide is presented. Also, approximate design criteria for TE/sub 0n/ to TE/sub 0n'/ axisymmetric, TE/sub 01/ to TE/sub 11/ wriggle, and TE/sub 01/ to TM/sub 11/ bend converters are reviewed. Numerically solving the coupled mode equations, an optimized set of mode converters has been designed for conversion of a 2 millimeter wave TE/sub 03/ mode into TE/sub 11/. This set consists of axisymmetric TE/sub 03/ to TE/sub 02/ and TE/sub 02/ to TE/sub 01/ converters followed by a wriggle TE/sub 01/ to TE/sub 11/ converter. This mode converter set was fabricated and tested using a 3 kW, 137 GHz gyrotron. A TE/sub 11/ mode purity of better than 97% was achieved. The TE/sub 01/ to TE/sub 11/ wriggle converter was experimentally optimized for a measured conversion efficiency of better than 99% not including ohmic losses.
- Research Organization:
- Massachusetts Inst. of Tech., Cambridge (USA). Plasma Fusion Center
- DOE Contract Number:
- AC02-78ET51013
- OSTI ID:
- 5955281
- Report Number(s):
- DOE/ET/51013-173; PFC/RR-86-2; ON: DE86009075
- Country of Publication:
- United States
- Language:
- English
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