Design and development of a sheet-beam electron gun with large current for a THz traveling-wave tube

Xuyuan Chen¹, Lin Xu¹, Xiao Sun¹, Shengkun Jiang¹, Yasong Fan², Guang Yang², Zhifang Lyu¹, Tao Tang¹, and Zhaoyun Duan^1
1National Key Laboratory of Science and Technology on Vacuum Electronics in Chengdu, School of Electronic Science and Engineering, University of Electronic Science and Technology of China (UESTC), 611731 Chengdu, China
²Nanjing Sanle Group Co., Ltd,211800 Nanjing, China
Dedicated to Prof B N Basu

In this paper, the design, development and experimental investigation on a sheet-beam electron gun with large current for a THz traveling-wave tube (TWT), which can operate typically at 0.22 THz frequency, is reported. The cylindrical cathode is made of scandate, and the pencil electron beam is compressed into a sheet beam by an elliptical focusing electrode. The maximum beam current of 123.4 mA was predicted with the emission current density of 24.56 A/cm² in simulation with 22 kV beam voltage. In the sheet-beam electron gun, the distance between the emission surface of the cathode and the beam-waist was found as 11 mm, and the wide edge and narrow edge of the beam waist cross-section are 0.38 mm and 0.1 mm, respectively. The components of the sheet-beam electron gun were fabricated and subsequently assembled. Its assembly errors were detected. The simulation predicts that the beam transportation in the sheet-beam electron gun under the condition of assembly errors exceeds 96%. The study also includes the experimental characterization of the cathode emission of the gun. The preliminary experimental results of the sheet-beam electron gun indicate that the beam current of 80 mA with the beam voltage of 22 kV was obtained from the proposed design. The experiment remained useful towards development of a 0.22 THz futuristic TWT. © Anita Publications. All rights reserved.
Keywords: Sheet beam, Electron gun, Terahertz TWT.

Peer Review Information
Method: Single- anonymous; Screened for Plagiarism? Yes
Buy this Article in Print © Anita Publications. All rights reserve

References

1. Booske J H, Plasma Physics and Related Challenges of Millimeter-Wave-to-Terahertz and High Power Microwave Generation, Phys Plasmas,15(2008)055502; doi.10.1063/1.2838240
2. Siegel P H, Terahertz Technology, IEEE T Microw Theory, 50(2002)910–928.
3. Kleiner R, Filling the Terahertz Gap, Science, 318(2007)1254–1255.
4. Carr G L, Martin M C, W R Mckinney, Jordan K, Neil G R, Williams G P, High-Power Terahertz Radiation from Relativistic Electrons, Nature, 420(2002)153–156.
5. Siegel P H, Terahertz Technology in Biology and Medicine, IEEE T Microw Theory Techn, 52(2004)2438–2447.
6. Woolard D L, Brown E R, Pepper M, Kemp M, Terahertz Frequency Sensing and Imaging: A Time of Reckoning Future Applications ?, P IEEE, 93(2005)1722–1743.
7. Booske J H, Dobbs R J, Joye C D, Kory C L, Neil G R, Park G S, Park J, Temkin R J, Vacuum Electronic High Power Terahertz Sources, IEEE T THz Sci Techn, 1(2011)54–75.
8. Srivastava V, THz Vacuum Microelectronic Devices, J Phys Conf Ser, 114(2008)012015; doi.10.1088/1742-6596/114/1/012015.
9. Field M, Griffith Z, Young A, Hillman C, Brar B, Gamzina D, Barchfield R, Zhao J, Spear A,  Anisullah Baig, Domier C, Barnett L, Luhmann N (Jr), Kimura T, Atkinson J, Grant T, Goren Y, Reed T, Rodwell M, Development of a 220 GHz 50 W Sheet Beam Travelling Wave Tube Amplifier, IEEE International Vacuum Electronics Conference, 2014, p 225–226.
10. Jiang S, Tang X, Huang S, Lyu Z, Wang Z, Tang T, Gong H, Gong Y, Duan Z, Metamaterial-Inspired 0.22 THz Traveling-Wave Tubes with Double Sheet Beams, IEEE T Electron Dev, 70(2023)1306–1311.
11. Liang H, Ruan C, Xue Q, Feng J, An Extended Theoretical Method Used for Design of Sheet Beam Electron Gun, IEEE T Electron Dev, 63(2016)4484–4492.
12. Swati M V, Baghel G S, Systematic Design Study of the Elliptical Sheet Beam Electron Gun for Terahertz TWT Applications, IEEE T Plasma Sci, 48(2020)3854–3861.
13. Lyu Z, Zhang C, Wang Z, Jiang S, Ruan C, Feng J, Gong Y, Duan Z, Terahertz Sheet Beam Vacuum Electron Devices, J Infr Millim Waves, 42(2023)26–36.
14. Carlsten B E, Russell S J, Earley L M, Krawczyk F L, Potter J M, Ferguson P, Humphries S, Technology Development for a mm-Wave Sheet-Beam Traveling-Wave Tube, IEEE T Plasma Sci, 33(2005)85–93.
15. Jiang S, Duan Z, Yang G, Jin L, Zhan X, Tian H, Wang Z, Gong H, Gong Y, Sheet Beam Electron Gun with High Current for 220 GHz TWT, 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW THz), 2018, p1-2.
16. Field M, Kimura T, Atkinson J, Gamzina D, Luhmann N C, Stockwell B, Grant T J, Griffith Z, Borwick R, Hillman C, Brar B, Reed T, Rodwell M, Shin Y-M, Barnett L R, Baig A, Popovic B, Domier C, Barchfield R, Zhao J, Higgins J A, Goren Y, Development of a 100-W 200-GHz High Bandwidth mm-Wave Amplifier, IEEE T Electron Dev, 65(2018)2122–2128.
17. Jiang S, Yang G, Wang Z, Wang X, Zhang X, Lyu Z, Tang T, Gong H, Gong Y, Duan Z, Experimental Investigation of a Shape-Optimized Staggered Double-Vane Slow-Wave Structure for Terahertz Traveling-Wave Tubes, IEEE T Electron Dev, 69(2022)4632–4637.
18. Duan Z, Jiang S, Yang G, Tang T, Wang Z, Gong H, Gong Y, Tang Y, Pan P, Cai J, Feng J, Experimental Advances in 220 GHz Sheet-Beam Traveling-Wave Tubes, 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 2019, p 1-2.
19. Jiang S, Wang X, Zhang X, Lyu Z, Wang Z, Gong H, Gong Y, Duan Z, Experimental Investigation of an Electron-Optical System for Terahertz Traveling-Wave Tubes, IEEE T Electron Dev, 68(2021)6498–6504.
20. Baig A, Gamzina D, Kimura T, Atkinson J, Domier C, Popovic B, Himes L, Barchfeld R, Field M, Luhmann N C (Jr), Performance of a Nano-CNC Machined 220-GHz Traveling Wave Tube Amplifier, IEEE T Electron Dev, 64(2017)2390–2397.
21. Ives R L, Microfabrication of High-Frequency Vacuum Electron Devices, IEEE T Plasma Sci, 32(2004)1277–1291.
22. Atkinson J E, Gajaria D D, Grant T J, Kimura T, Stockwell B C, Field M, Borwick R J, Braral B, Pasour J A, A High Aspect Ratio High Current Density Sheet Beam Electronic Gun, 2010 IEEE International Vacuum Electronics Conference (IVEC), 2010, p 97–98.
23. Srivastava A, Jin-Kyu S, W Yiman Wang, et al., Design of Sheet-Beam Electron Gun with Planar Cathode for Terahertz Devices, J Infr Millim THz Waves, 30(2009)670-678.
24. Tang X, Duan Z, Wang Z, Tang T, Wei Y, Cong Y, The Design Method of Millimeter-Wave Sheet-Beam Electron Gun, J Infr Millim Waves, 33(2014)619–624.
25. Longo R T, A Study of Thermionic Emitters in The Regime of Practical Operation, 1980 International Electron Devices Meeting, Washington, 1980, p 467–470; doi: 10.1109/IEDM.1980.189868.
26. Langmuir I, The Effect of Space Charge and Residual Gases on Thermionic Currents in High Vacuum, Phys Rev, 2(1913)450–486.
27. Richardson O, On the Positive Ionization Produced by Hot Platinum in Air at Low Pressures, Philos Mag, 6(1903) 80–96.
28. Pierce J R, Rectilinear Electron Flow in Beams, J Appl Phys, 11(1940)548–554.
29. Pierce J R, Theory and Design of Electron Beams, (Princeton, NJ, USA: Van Nostrand), 1954.