Abstract:
Generation and amplification of RF waves in the millimeter wave and
submillimeter wave frequency range is of importance to applications in high
resolution radar and high information density communication, deep space and
specialized satellite communication, advanced high gradient RF linear
accelerators, plasma diagnostics and chemistry, material processing, waste
remediation, ceramic sintering, laser pumping, power beaming and electron
cyclotron resonance (ECR) heating of fusion plasmas, radar and imaging in
atmospheric and planetary science, and nonlinear spectroscopy. However, there
exists a technology gap for active devices in this frequency range. The
conventional microwave tubes are not capable to generate high power at
millimeter and submillimeter wave frequencies due to shrinking of their cross sectional dimension with frequency. For quantum-optical devices, like, lasers, it
is difficult to sustain the population inversion with the reduction of the energy of
each quantum in the lower frequency region. Therefore, during the past few
decades, intensive research and development efforts have been made towards high
power coherent gyro-sources and gyro-amplifiers in this frequency range. In
gyro-devices, the problem of miniaturization of transverse dimensions with
frequency has been tackled by using overmoded RF circuits, i.e., cavities and
waveguides, thereby dramatic increase in their transverse dimension due to
operation in the higher order modes.
