Compact quasi-periodic and aperiodic TE0n modeconverters in overmoded circular waveguides for use with gyrotrons |
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Authors: | Buckley MJ Vernon RJ |
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Affiliation: | Dept. of Electr. & Comput. Eng., Wisconsin Univ., Madison, WI; |
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Abstract: | Designs of compact quasi-periodic and aperiodic TE0n-TE 0n-1 circular waveguide converters for use with gyrotrons in an electron cyclotron heating (ECH) system are developed by analytically and numerically solving the coupled-mode differential equations. Quasi-periodic mode transducer designs which convert the TE02 mode to the TE01 mode, and in some cases also include a taper (waveguide radius reduction), are developed. A 60-GHz aperiodic mode converter-taper combines a 6.35-cm-2.779-cm waveguide diameter taper and a TE02-TE01 mode converter. A 140-GHz aperiodic mode converter-taper combines a 6.35-cm-2.779-cm waveguide diameter taper and a TE03-TE02-TE01 mode converter. The resulting designs are highly efficient (conversion efficiencies ⩾99.4%), are shorter, have a broader bandwidth than previous designs, and have a waveguide radius greater than or equal to 1.389 cm over the entire length of the transducer to allow for high-power transmission. Experimental results consistent with theoretical calculations are presented |
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