Terahertz Large-Orbit High-Harmonic Gyrotrons at IAP RAS: Recent Experiments and New Designs

CW subterahertz gyrotron operating at high cyclotron harmonics

“…Further prospects for the development of this LOG are based on increasing the accelerating voltage of particles to 35-45 kV and increasing the operating magnetic field to 6 T. This will make it possible to achieve a fourth harmonic operation at frequency of 0.65 THz which is also demanded from NMR spectroscopy. In the first experiments, the operation of CW LOG at the second and third cyclotron harmonics was obtained in pulsed regimes (from 10 μs to 0.3 s) [2]. Then LOG was tested in long pulse (several seconds) and CW generation regimes.…”

“…Taking into account the fact that the electron efficiency at the fourth harmonic is also rather low (approximately 2%), the output gyrotron efficiency in such conditions is less than 0.1%. To improve the third harmonic LOG operation as well as to provide selective fourthharmonic generation, quasi-regular cavities with periodic phase correctors based on the gyrotron excitation of far-from-cutoff longitudinal modes with relatively low Q-factor [2]. To provide the LOG's fourth harmonic excitation, a cavity consisting of five sections separated by phase correctors was developed and calculated (Fig.…”

“…In the first experiments, the generation at the second and third cyclotron harmonics with a power of hundreds of watts in a wide (0.55 -1.0 THz) frequency range with operating magnetic fields of 10-14 T was obtained. The "continuous LOG" setup [2] is being developed as a prototype of a multifrequency source for spectroscopic applications. It is based on the use of a cryomagnet (5 T) and an axial 30 keV / 0.7A electron beam.…”

“…To date, generation at the second and third harmonics in the longpulse (~ 0.1 s) and CW regimes has been obtained in this gyrotron. To ensure the selective excitation of the fourth cyclotron harmonic as well as to improve the gyrotron operation at the third harmonic, special extended sectioned cavities with reduced diffraction Q-factors of the operating modes are being developed [2,3].…”

Short-wavelength gyrotrons with quasi-regular and sectional cavities

“…Traditional high-power subterahertz gyrotrons, demanded by a number of important modern applications, provide radiation power up to 1 MW in the quasi-continuous regime at frequencies up to 0.17 THz and about 1 kW [1] in long pulses at frequencies up to 1.3 THz [2]. At the same time, to achieve a frequency about 1 THz, strong magnetic fields (over 30 Tesla) are required.…”