Comparison of two gyroklystron concepts: frequency multiplication versus operation at a given cyclotron harmonic

For many gyrotron applications the critical issue is the use of cryomagnets or heavy and bulky solenoids. Since in gyrotrons the magnetic field required for obtaining the radiation at a given frequency is inversely proportional to the cyclotron harmonic number, s, the gyrotron operation at harmonics (s >1) has been studied for a long time. In multi-stage gyro-amplifiers two concepts of harmonic operation are known: regime of frequency multiplication (for instance, operation of the input stage at the ftindamental cyclotron resonance, s₁=1, and the output stage operation at the harmonic, s₂>1) and operation of all stages at the same harmonic s₁ =s₂>1. Both concepts have been actively studied for a long time. However, so far, no comparative analysis of these two concepts and their potentials has been carried out. Below, we describe an attempt to do such analysis.