0000000000114169
AUTHOR
Toshitaka Idehara
High Cyclotron Harmonics Excitation in Multi-beam Terahertz Range Gyrotrons
The paper presents recent results on the multi-beam gyrotrons operating at cyclotron harmonics in terahertz frequency range. The theoretical and experimental investigation of second harmonic 0.78 THz gyrotron includes comparison of generating and absorbing beam schemes, research on the effect of velocity spread and mode competition process, along with development of third harmonic 1.2 THz tube based on verified numerical codes and latest experimental results.
Using of reflections for expansion of frequency tuning in a THz-band gyrotron
Effect of delayed reflection on operation of a second-harmonic THz-band gyrotron is studied. Theoretical analysis, numerical calculations and experimental observations for the 0.394 THz FU CW IIB gyrotron are presented.
Experimental verification of a self-consistent calculation for continuous frequency-tune with a 400 GHz band second harmonic gyro-BWO
A self-consistent code is introduced to develop a continuous frequency tunable gyro-BWO. A cavity is designed with TE8,5 mode for 400 GHz band second harmonic oscillation. The experimental verification has been carried out and 2 GHz tunability is observed with output powers of higher than 40 W.
Hysteresis and frequency tunability of gyrotrons
We present the first devoted experimental and theoretical study of hysteresis phenomenon in relation to frequency tunability of gyrotrons.
Study of Mode Competition in the Third Harmonic Gyrotron with Inclusion of the Electron Velocity Spread and the Beam Width
Influence of the electron velocity spread and the beam width on the mode competition and efficiency is investigated in the 1.185- THz third harmonic gyrotron to be used in dynamical nuclear polarization - nuclear magnetic resonance (DNP-NMR) spectrometer.
Calculations of Starting Currents and Frequencies in Frequency-Tunable Gyrotrons
Cold cavity and self-consistent formalisms for starting current and frequency calculations in frequency-tunable gyrotrons are summarized. Numerical solution schemes of the corresponding equations are discussed. A specific case is analyzed in detail.