Session chairperson and summary author: Thomas Hargreaves
Seventeen posters were presented during Poster Session I, covering a wide range of topics including slow-wave circuit design, electron gun development, and fast-wave device experiments.
Hargreaves (Northrop Grumman), et al., presented work on the optimized design of helix traveling wave tubes (TWTs). Various designs were compared with respect to output power, gain, and third order intermodulation products.
Han (Seoul National University), et al., described the design of a folded waveguide TWT. The design was done with analytic theory and the three dimensional codes HFSS and MAGIC3D. Another geometry, the coaxial inverted helical groove slow-wave structure, was presented by Wei (Seoul National University), et al. The cold circuit parameters were calculated via analytic theory and checked with HFSS for the structure comprised of a smooth outer wall and a coaxial inner conductor with a helical groove.
Kageyama (NEC Corporation) detailed a methodology to design a low VSWR match from a coupled cavity circuit to waveguide. The methodology uses a modified Curnow equivalent circuit model and requires a transition region in the circuit where cavity and coupling slot geometry are gradually changed from period to period to provide a broadband match. Another folded waveguide design was shown by Na (Kwangwoon University), et al. The two stage circuit design was centered at Q-band (44Ghz) and is predicted to produce 200 watts of saturated power.
Wilson (NASA Glenn Research Center), et al., described the implementation of discrete-state simulated annealing methodology and compared it to the more traditional use of simulated annealing. The two methods were compared to the optimization of a TWT circuit showing much shorter optimization times for discrete-state simulated annealing.
Ives (Calabazas Creek Research, Inc.), et al., showed work done on the design, fabrication and testing of a magnetron injection gun. The testing utilized a segmented anode that enabled the measurement of the gun current at 60 locations, allowing direct measurements of the azimuthal asymmetry of the cathode emission. A tetrode gridded gun having diode gun beam properties was described by Theiss and True. This gun is useful for high power millimeter wave TWTs. A unique beam concentricity measurement scheme was shown.