Coaxial-waveguide gyrotron amplifier operating with high power and ultrahigh gain in Millimeter and submillimeter waves

A coaxial-waveguide gyrotron-traveling wave amplifier is proposed, which may be suitable for the operation in the spectrum of the short millimeter and submillimeter waves with good mode selectivity, high power, and ultrahigh gain. An example is presented in terms of the linear gyrokinetics and nonlinear simulations. Theoretical results show that tens of kilowatts with ultrahigh gain up to 67 dB might be achieved for the operation of the coaxial-waveguide mode TE_28,16 in the fundamental cyclotron harmonic at the frequency of 140 GHz. The power enhancement by a tapered magnetic field is discussed.