Beam-Wave Coupling Strength Analysis in a Gyrotron Traveling-Wave Amplifier

Abstract

Mode competition is an important aspect of the stability analysis of a gyrotron traveling-wave amplifier (gyro-TWT). The concept of the coupling impedance is developed in this paper to investigate the beam-wave coupling strength in the electron cyclotron maser (ECM) interaction system. The coupling impedance brings a global consideration to study competition between the absolute instability and the convective instability in the circuit. The research reveals that the coupling impedance is proportional to the phase velocity of the mode, which means the coupling impedance of a mode in the lower k z region is much stronger than the one in the higher k z region. Interesting discussions are also carried out at the end of the paper. The coupling impedance provides an additional dimension of measurement to understand the ECM interaction.

Broadband terahertz-power extracting by using electron cyclotron maser

“…Electron beam and EM wave characteristics, especially frequency and phase velocity, are simultaneously included in K . The analytical expressions are given as 30 where H sm is the coupling coefficient, k ⊥ and k z are the transverse and longitudinal wave numbers, J m is the Bessel function of order m . Substituting the beam-wave equations in ref.…”