Numerical Study of Nonstationary Phenomena in Gyro-Oscillators

The possible applications of gyro-oscillators span a wide range of technologies [61 - 63]. In the field of magnetic confinement fusion studies, such applications as lower hybrid current drive, electron cyclotron resonance heating (ECRH) and current drive, plasma production for different processes, and active plasma diagnostic measurements have been demonstrated. For these applications, it is necessary to develop CW gyromonotrons that operate at both higher frequencies and higher output power. Hence single-mode 110-170 GHz CW gyromonotrons with a conventional cylindrical cavity, capable of high average power (0.5-1 MW per tube), and 2 MW coaxial cavity gyromonotrons are currently under development. Gyromonotrons are also successfully used in materials processing (e.g. in advanced ceramic sintering, surface hardening, or dielectric coating of metals and alloys) as well as in plasma chemistry. The use of gyromonotrons for such technological applications appears to be of interest if one can realize a relatively simple, low cost device which is easy in service. Hence gyromonotrons with low magnetic field (operating at the 2nd harmonic of the electron cyclotron frequency), low anode voltage, high efficiency, and long lifetime are under development. Potential applications of gyro-BWOs as a tunable millimeter-wave source including position-selective heating of fusion plasma, spectroscopy, materials processing, and drivers for ultra-high power amplifiers also motivate further theoretical and experimental investigations.