Electron Gun and Output Coupling System for a 220-/251.5-GHz, 2-MW Triangular Corrugated Coaxial Cavity Gyrotron

In this paper, design studies of a common electron gun and output coupling system for the dual regime operation of a 2-MW coaxial cavity gyrotron are presented. The operating frequencies (220/251.5 GHz) are selected, such that the proposed gyrotron can be used for plasma heating applications in the future experimental fusion reactors. A coaxial magnetron injection gun (MIG) is designed for the generation of hollow electron beam with the desired parameters. Initial geometry of the electron gun is determined through our in-house code Gyrotron Design Suite version 4.1 2016 (GDSv4.1 2016). The MIG is further optimized and simulated through the beam trajectory code ESRAY. A nonlinear taper (NLT) is designed with maximum transmission efficiency at both the operating frequencies. A quasi-optical launcher (QOL) is designed and numerically optimized through the commercial software, launcher optimization tool. The designed launcher efficiently converts both the operating modes into Gaussian-like mode. A single-disk RF window is designed for the extraction of high-power output beam from the gyrotron at their respective operating frequencies. The design of the NLT and the RF window are carried out through GDSv4.1 2016.

[1]  Stefan Illy,et al.  I/O System for A 77/154-GHz, 0.5-MW Dual Regime Gyrotron , 2016, IEEE Transactions on Electron Devices.

[2]  S. Illy,et al.  Gyrotron electron gun and collector simulation with the ESRAY beam optics code , 2015, 2015 IEEE International Vacuum Electronics Conference (IVEC).

[3]  M. Thumm,et al.  Further design steps towards a 4 MW 170 GHz coaxial-cavity gyrotron , 2009, 2009 34th International Conference on Infrared, Millimeter, and Terahertz Waves.

[4]  John Jelonnek,et al.  Towards a 0.24-THz, 1-to-2-MW-class gyrotron for DEMO. , 2015 .

[6]  W. Lawson,et al.  The design of a high peak power relativistic magnetron injection gun , 1986 .

[7]  M. V. Kartikeyan,et al.  Full Wave Analysis of Coaxial Gyrotron Cavity With Triangular Corrugations on the Insert , 2017, IEEE Transactions on Electron Devices.

[8]  R. Ives,et al.  Controlled porosity cathodes from sintered tungsten wires , 2005, IEEE Transactions on Electron Devices.

[9]  W. Lawson,et al.  Magnetron injection gun (MIG) design for gyrotron applications , 1986 .

[10]  K. Yokokura,et al.  Development of a dual frequency (110/138 GHz) gyrotron for JT-60SA and its extension to an oscillation at 82 GHz , 2015 .

[11]  B. Piosczyk.  A COAXIAL MAGNETRON INJECTION GUN (CMIG) FOR A 2 MW, 170 GHz COAXIAL CAVITY GYROTRON , 2006 .

[12]  Manfred Thumm,et al.  State-of-the-Art of High Power Gyro-Devices and Free Electron Masers. Update 2016 (KIT Scientific Reports ; 7735) , 2017 .

[13]  M. V. Kartikeyan,et al.  RF Behavior of a 220/251.5-GHz, 2-MW, Triangular Corrugated Coaxial Cavity Gyrotron , 2017, IEEE Transactions on Electron Devices.

[14]  G. Gantenbein,et al.  Status of the new multi-frequency ECRH system for ASDEX Upgrade , 2007, International Conference on Plasma Science.

[15]  G. Gantenbein,et al.  2 MW, 170 GHz coaxial-cavity short-pulse gyrotron — Single stage depressed collector operation , 2014, 2014 39th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz).

[16]  K. Sakamoto,et al.  Development of multi-frequency gyrotron for ITER and DEMO at QST , 2016, 2016 41st International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz).

[17]  T. Rzesnicki,et al.  Theoretical investigation of an advanced launcher for a 2-MW 170-GHz TE/sub 34,19/ coaxial cavity gyrotron , 2006, IEEE Transactions on Microwave Theory and Techniques.