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Item type:Publication, Access status: without files , Impact of Asymmetric Beam Shapes on the Body Current and BWO Margin in Helix TWTs(2022-01-01); ; The effects of asymmetric beam shapes, caused by geometric asymmetries of the electron gun or asymmetries of the magnetic focusing system, on the body current and the sensitivity to backward wave oscillations (BWO) are investigated by simulation. It is found that asymmetric beams can significantly increase the body current and the sensitivity to BWO.Publicationtype: Conference Paper53 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Drive-induced backward-wave oscillations in helix traveling-wave tubes -- a case studyThe output section of helix traveling-wave tubes (TWTs) usually features a tapered delay line to enhance the amplifier performance. This alters the phase velocity of the circuit waves, which, in particular, disturbs the narrowband synchronism between the backward wave (BW) and the electron beam. As a result, the excitation threshold of BW oscillations (BWOs) increases. Large-signal operation significantly alters beam-wave synchronism, as the electrons loose kinetic energy during the amplification process, i.e., toward the TWT output. As a result, beam and BW may interact over a larger distance, thus lowering the threshold for the onset of BWOs. These would thus be drive-induced in contrast to the zero-drive BWOs mentioned above. The following investigates the occurrence of such drive-induced BWOs as a case study of several different TWT models and proposes a theory for the large-signal instability. As the simulation process is quite involved and time-consuming, a heuristic approach for the fast prediction of the oscillation is presented as well.Publicationtype: Journal Article93 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , 1-D simulation of backward-wave and Pi-mode oscillations in helix traveling-wave tubes(2021-04-29); ; Publicationtype: Conference Paper118 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Simulation of drive-Induced oscillations in helix traveling-wave tubes(2021-01); ; Publicationtype: Journal Article143 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Stopband and coupling-coefficient estimation for asymmetries in helical delay-lines(2020-10); ; Publicationtype: Conference Paper104 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Analysis of power holes in helix traveling-wave tubes with non-uniform delay-lines(2020-10); ; ; Publicationtype: Conference Paper74 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , 102 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Improving traveling-wave tubes for modulated operation in back-off(ITG Informationstechnische Gesellschaft im VDE, 2018-09); ; Publicationtype: Conference Paper36 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Oscillation Starting Current Approximation by Time-Domain Simulation in Traveling-Wave Tubes(ITG Informationstechnische Gesellschaft im VDE, 2018-09); ; Publicationtype: Conference Paper39 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A Traveling-Wave Tube Simulation Approach with CST Particle Studio(2018-06); ; ; Commercial Ku-band tapered helix traveling-wave tubes (TWTs) and a folded-waveguide Q-band TWT are modeled and simulated in CST Particle Studio (PS) on a desktop computer. Efficient models for the electron beam, the severs, and the delay line are investigated to enable accurate and automatable model generation, simulation, as well as pre- and postprocessing. The results of particle-in-cell simulation in CST PS are presented and compared to those of the specialized steady-state simulation codes MVTRAD and KlysTOP, as well as to measurements.Publicationtype: Journal Article291