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The new concept of symmetric (double-folded) and asymmetric (single-folded) folded meander-line slow-wave structures is proposed for broader bandwidth and higher interaction impedance characteristics, respectively. The structures are analyzed using 3D numerical simulation in CST-Microwave Studio for the dispersion and interaction impedance characteristics at Ka- and W-bands. The results are compared...
A new class of Multi helix based THz vacuum electron devices is under consideration easily fabricated using unconventional applications of microfabrication technology and modern computer modeling. This configuration will extend the operating range of the helical slow wave circuit into the THz frequency band. The design of a ∼140 GHz amplifier is described, which can be extended beyond 1.0 THz.
Analysis of a W-band meander-line slow-wave structure has been carried out using quasi-TEM approach and validated against CST-Microwave studio for the dispersion and interaction impedance characteristics. A waveguide coupler is designed using HFSS and large signal analysis is carried out for output power and gain. A cold test model of the structure is fabricated at Ku-band frequency and cold test...
This paper describes the simulations of a single-stage depressed collector and a 3-stage depressed collector including the effects of secondary electron emission (SEE) using a 2D FDM based code PIERCE and compares the single-stage collector efficiency against experimental results at different frequencies.
This paper briefly presents the details of the design of a K-Ka band, 40 W CW, millimeter-wave helix TWT. Sub-system level design and TWT development issues are also presented.
Nonlinear analysis of a high-power gyro-TWT amplifier operating in TE01 mode has been investigated through particle-in-cell (PIC) simulation using CST-studio. The simulation results are validated against published results with close accuracy. The simulation predicts 150 kW output power at 34 GHz with 21% efficiency, 48 dB saturated gain and 1.3 GHz bandwidth.
Electromagnetic field analysis of a helical slow-wave structure was carried out following tape-helix model incorporating the effects of space-harmonic propagating modes and the effects of finite width of the tape. Using this analysis, RF loss in the structure due to the finite conductivities of the constituent materials was estimated. The analysis was validated against published results for a segment-less...
Slow-wave characteristics of a broadband `semi-vane' helical SWS have been studied using 3D electromagnetic modeling in CST-studio. The geometry has shown promises for better broadbanding potential compared to a conventional segment loaded configuration. Also, the results have shown that placement of segments closer to the support rods provides a better negative dispersion.
Small-signal analysis of a plasma-filled helix traveling-wave tube was developed following Eulerian hydrodynamic approach. The electron beam was treated as a moving charged fluid and the plasma a stationary quasi-neutral fluid. The coupled circuit and electronic equation was developed and a Pierce-type hot dispersion relation obtained, which was then interpreted for the gain-frequency response of...
In a broadband coupled-cavity slow-wave structure, the problem of bandedge oscillation is overcome by resonant loss technique by introducing lossy dielectric resonators in the cavity. To reduce the dimensions of the dielectric resonators, high lossy and high dielectric constant, materials are used. In this paper, the effects of introducing 2, 4 and 8 lossy dielectric resonators (operating either on...
This paper describes the simulation of an axi-symmetric 2-stage depressed collector including the effects of secondary electrons using a 2D FDM based code and compares its efficacy against experimental results and 3D simulation using CST Particle Studio. The paper also demonstrates the 3D simulation of a tilted electric field (TEF) collector using CST Studio for arresting the secondary electron back-migration.
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