THz gyrotron and BWO designed for Operation in DNP-NMR Spectrometer magnet

Dynamic nuclear polarization (DNP) in high-field nuclear magnetic resonance (NMR) spectroscopy requires medium-power terahertz radiation, which nowadays can be provided basically by gyrotrons with superconducting magnets. As the electron cyclotron frequency is very close to the frequency of electron paramagnetic resonance for the same magnetic field, under certain conditions the gyrotron can be installed inside the same solenoid used for NMR spectrometer. This eliminates the need for an additional superconducting magnet, results in a shorter terahertz transmission line, and can make DNP systems practical. In addition to an extremely low-voltage gyrotron ("gyrotrino"), we analyze also advantages of strong magnetic field for a slow-wave electron device as an alternative terahertz source

Single-Cavity Gyromultipliers

Abstract: Several new configurations of self-exciting gyro-multipliers are proposed. These schemes allow concurrent excitation of radiation at fundamental and harmonic frequencies in a single resonator. It is shown that such an approach simplifies the experimental setup and promises high device efficiency. Experimental proposals based on some of the schemes are presented

Planar Bragg Reflectors for Frequency-Tunable Sub-Terahertz Gyrotrons

A novel concept of a frequency-tuned sub-terahertz gyrotron based on a combination of an irregular low-frequency resonator and an external reflector has been proposed recently. A simulation was carried out for a fundamental-cyclotron-harmonic gyrotron that demonstrates the possibility of achieving high (10–30%) efficiencies in a wide (~10%) frequency range. A possible solution to the problem of narrow-band frequency-tunable external reflectors in the form of so-called modified planar Bragg structures is discussed. The manufacturing of such structures on the basis of a novel additive technology based on photopolymer 3D printing, as well as the results of “cold” experiments of the manufactured samples, are described in the paper