experimerits is described. The converter conserves the power □f all circular symmetric modes emitted by a gyrotron and aligns the fields into linearly polarized modes required ■For effective plasma, heating by electron cyclotron or by lower hybrid resonance absorption. It also allows a convenient combination of the power output of several klystrons and mode conversion into modes with low attenuation. Suitable combinations of waveguide diameter and number of sectors dividing (or combining) the power avoid the excitation of unwanted modes. (Author (ESA)) Source of Abstract (Subfile): ESA Keywords: *BEAM WAVEGUIDES; *EXTREMELY HIGH FREQUENCIES; *MDDE TRANSFORMERS; *F'LASMA HEATING; ♦WAVEGUIDES; CYCLOTRON RESONANCE DEVICES; KLYSTRONS; LINEAR POLARIZATION Subject Classification: 7575 Plasma Physics (1975-) High power millimeter-wave mode converters in overmoded circular waveguides using periodic wall perturbati ons. THUMM, M. Stuttgart Univ. (West Germany). Inst, fuer P1asmaforschung. Corp . Source Code: S4355674 Jul. 1984. 4 IP. Presentat i on Note: Presented at Intern. Symp. on Gyrotron Develop., Lausanne, Switzerland, 4-6 Jul. 1984. Report No.: IPF-84-6 L anguage: E ng1i sh. Country of Origin: Germany, Federal Republic of. Country of Publication: Germany, Federal Republic of Document Type: CONFERENCE PAPER Most documents available from AIAA Technical Library Other Availability: NTIS HC A03/MF AOI Journa1 Announcement: STA R8509 Conversion of circular electric TEOn gyrotron mode compositions at 28 and 70 GHz to the linearly polarized TE11 mode is described. Mode transducers with axisymmetric radius perturbations transform the TEOn gyrotron mode mixture to TE01 mode for long-distance transmission through overmoded waveguides. A mode converter with constant diameter and periodically perturbed curvature transfers the unpolarized TE01 mode into the TE11 mode which produces an almost linearly polarized millimeterwave beam needed for efficient electron cyclotron heating of plasmas in thermonuclear fusion devices. The TEOn-to-TEO1 conversion efficiency is 98+or-lZ at 28 and 70 GHz, while the TEOl-to-TEll converter has a 96+or—27. conversion efficiency at 28 GHz and 94+or-2Z at 70 GHz; ohmic losses are included. For TE16-to-TE12-to-TEl1 mode conversion at 28 GHz by 2 periodically rippled wall mode converters, efficiencies are 927. and 957., respectively. (Author (ESA)) Source of Abstract (Subfile): ESA Keywords: *CYCL0TR0N RESONANCE DEVICES; *El_ECTR0N CYCLOTRON HEATING; *MILL IMETER WAVES; *MODE TRANSFORMERS; BEAM WAVEGUIDES; LINEAR POLARIZATION ; MICROWAVE COUPLING Subject. Classification: 7575 Plasma Physics (1975--)
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