Coaxial gyrotrons: past, present, and future (review)

• Published in: IEEE transactions on plasma science Vol. 32; no. 3; pp. 934 - 946
• Main Authors: Dumbrajs, O., Nusinovich, G.S.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2004; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Coaxial components; Fusion reactors; Gyrotrons; Klystrons; Linear accelerators; Manufacturing; Microwave circuits; Millimeter wave circuits; Oscillators; Plasma; Plasma density; Plasma materials processing
• ISSN: 0093-3813; 1939-9375
• DOI: 10.1109/TPS.2004.829976

Most of the present-day millimeter-wave gyrotrons developed for plasma experiments in controlled fusion reactors utilize cylindrical cavities operating in high-order modes. The choice of modes should obey certain restrictions dictated by the achievable mode selection and the maximum admissible level of the density of microwave ohmic losses in the cavity walls. Even with these restrictions, developers have successfully manufactured quasi-continuous-wave gyrotrons operating in the short millimeter wavelength bands that are capable of delivering microwave power on the order of 1 MW. To upgrade gyrotron power to the level of several megawatts, more complicated coaxial microwave circuits should be used. This statement is also valid for relativistic gyroklystrons, which are currently under development for driving future linear accelerators. This paper presents an overview of the history of the development of coaxial gyrodevices, a discussion of the physics-based issues which are the most important for their operation, a description of the state of the art in the development of coaxial gyrodevices for the above-mentioned applications, and a brief forecast for their future.