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기술보고서

기술보고서 게시판 내용
타이틀	Computer Analysis of Spectrum Anomaly in 32-GHz Traveling-Wave Tube for Cassini Mission
저자	James A.Dayton, Jr., Jeffrey D. Wilson, and Carol L. Kory
Keyword	Traveling-wave tube; Cassini; Ka-band; Slow-wave circuit
URL	http://gltrs.grc.nasa.gov/reports/1999/TP-1999-208691.pdf
보고서번호	NASA TP-1999-208691
발행년도	1999
출처	NASA Glenn Research Center
ABSTRACT	Computer modeling of the 32-GHz traveling-wave tube (TWT) for the Cassini Mission was conducted to explain the anomaly observed in the spectrum analysis of one of the flight-model tubes. The analysis indicated that the effect, manifested as a weak signal in the neighborhood of 35 GHz, was an intermodulation product of the 32-GHz drive signal with a 66.9-GHz oscillation induced by coupling to the second harmonic signal. The oscillation occurred only at low-radiofrequency (RF) drive power levels that are not expected during the Cassini Mission. The conclusion was that the anomaly was caused by a generic defect inadvertently incorporated in the geometric design of the slow-wave circuit and that it would not change as the TWT aged. The most probable effect of aging on tube performance would be a reduction in the electron beam current. The computer modeling indicated that although not likely to occur within the mission lifetime, a reduction in beam current would reduce or eliminate the anomaly but would do so at the cost of reduced RF output power.