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In this paper, we describe the design and development of helical cut smooth wall mode launcher for high frequency and high power Gyrotron. A Vlasov-type helical cut mode launcher for converting TE 22,6 mode to a Gaussian mode has been designed for 120 GHz, 1 MW Gyrotron. The initial design of mode launcher has been optimized using LOT/SURF-3D software. The mode launcher diameter and length are optimized considering the minimum return loss and the minimum insertion loss by using CST microwave studio. The return loss (S 11 ) and insertion loss (S 21 ) performance of helical cut smooth wall mode launcher have been obtained using CST-Microwave Studio. The fabrication of Vlasov-type helical cut mode launcher for 120 GHz Gyrotron has also been carried out. [ABSTRACT FROM AUTHOR]

A review on the sub-THz/THz gyrotrons is performed in this manuscript. The present development status of gyrotrons can be divided into three streams for the sake of better understanding: 1. low frequency (<35 GHz), medium power (<100 kW), small size and easy to handle gyrotrons for industrial applications, 2. very high power (1 MW or more), medium frequency (100–200 GHz) gyrotrons for plasma fusion applications, 3. low power (few tens of watt to kW), high frequency (>200 GHz) gyrotrons for various innovative applications. In this manuscript, the third stream of gyrotron development is reviewed. In last few decades several innovative applications are searched in sub-THz/THz band where the gyrotrons could be used as an efficient source of RF radiation. The applications of sub-THz/THz gyrotrons including the futuristic scope of the device are also discussed in this article. Further, several criticalities arise in the design and development when the gyrotron operation shifts toward the high frequency band. Various such design and technological challenges are also discussed here. Finally the development status of sub-THz/THz gyrotrons as per the use in various scientific and technological applications is also discussed. [ABSTRACT FROM AUTHOR]

The design study of dual frequency gyrotron operating at 42/84 GHz frequencies with output power ∼500 kW is presented in this article. TE 10,4 and TE 6,2 are selected as the operating modes for 84 and 42 GHz operations of the device, respectively. The beam-wave interaction simulations are performed by using the Particle-in-Cell algorithm to evaluate the growth of RF power and frequency. Magnetically tunable magnetron injection gun is also designed to launch the electron beam at the radius of 6.2 mm (84 GHz) and 7.3 mm (42 GHz) in the interaction cavity. The CVD diamond RF window is also designed, which must be transparent for 42 GHz and 84 GHz frequencies. The design results of the dual frequency gyrotron confirm the growth of ∼500 kW power at 42/84 GHz. [ABSTRACT FROM AUTHOR]