Design and fabrication of a sub-millimeter multi-beam folded waveguide structure

Abstract

A novel multi-beam folded waveguide (MBFW) circuit, which can enhance the output power and interaction efficiency of sub-terahertz (THz) traveling wave tube (TWT), is presented in the paper. Operating with fundamental mode and multiple electron beams means that a larger beam current can be used for a higher output power. The characteristics of the MBFW structure are analyzed and optimized. Compared with the single-beam folded waveguide (SBFW) TWT, the output power of the MBFW TWT increases from 3.64 W to 25.45 W at 140 GHz and its electronic efficiency increases from 1.06% to 7.4% under the conditions of an input peak power of 10 mW, a beam voltage of 9.55 kV and a current of 12 mA. The optimized MBFW structure can be successfully fabricated by micro milling, with dimension errors below expectation, and the measured transmission characteristics are in good agreement with the design.

References

[1] SiegelP H. IEEE Transactions on Microwave Theory & Techniques, 2004, 52: 2438

[2] ShinY M, BaigA, BarnettL R, TsaiW C, LuhmannN C. IEEE Trans. Electron Devices, 2012, 59: 234

[3] GongH, GongY, TangT, XuJ. IEEE Trans. Electron Devices, 2011, 58: 2159

[4] NusinovichG S, CookeS J, BottonM, LevushB. Physics of Plasmas, 2009, 16: 853

[5] DeanE P, KhanhT N, DavidK A. IEEE Trans. Electron Devices, 2014, 61: 1637

[6] FieldM, GriffithZ, YoungA, HillmanC. Development of a 220 GHz 50 W Sheet Beam Travelling Wave Tube Amplifier, 2014, 225

[7] KoryC L, ReadM, IvesR L, BooskeJ, BorchardP. IEEE Trans. Electron Devices, 2008, 56: 713

[8] KreischerK E, TucekJ C, BastenM A, GallagherD A. 220 GHz Power Amplifier Testing at Northrop Grumman, 2013, 1

[9] BastenM A, TucekJ C, GallagherD A, KreischerK E. G-Band Power Module Development at Northrop Grumman, 2013, 1

[10] YanS, SuW, WangY, XuA. IEEE Trans. Plasma Science, 2015, 43: 414

[11] YanS, SuW, XuA, WangY. Journal of Electromagnetic Waves and Applications, 2014, 29: 436

[12] BooskeJ H, ConverseM C, KoryC L, ChevalierC T. IEEE Trans. Electron Devices, 2005, 52: 685