Operation of a millimeter-wave harmonic gyrotron

Submillimeter-wave large-orbit gyrotron

“…The modes were identified by the radiation frequency, the value of the resonant magnetic field, and measurements of the transverse structure of the high-frequency field on the output-horn aperture. Submillimeter-wave radiation was obtained for the 3rd cyclotron harmonic in the TE 3,8 and TE 3,9 modes. When measuring the frequency for a number of modes, we analyzed the beat signal of the synthesizer and gyrotron radiation (measurements were made by M. Yu.…”

“…As opposed to a conventional gyrotron in which electrons move along the helical trajectories whose axes are uniformly distributed over the circumference (or in a thin ring) with radius significantly exceeding the Larmor radius of particles, all particles in the LOGs perform the Larmor rotation round the cavity axis as they move along this axis. Due to asymmetry, such a near-axis beam can excite in the axisymmetric electrodynamic system only the modes whose azimuthal index coincides with the number of the resonant cyclotron harmonic [8,[16][17][18]. This strong rule of selection significantly rarefies the mode spectrum and thereby simplifies the selective excitation of high cyclotron harmonics compared with the case of a conventional gyrotron.…”

“…Along with the already realized unique sources such as conventional gyrotrons with very strong magnetic fields [1][2][3][4][5] and free-electron lasers [6,7], the so-called large-orbit gyrotrons (LOGs) [8][9][10][11][12][13][14][15], which previously operated in centimeter-and millimeter-wave ranges, seem to be more promising and, possibly, simpler for the case of submillimeter waves. As opposed to a conventional gyrotron in which electrons move along the helical trajectories whose axes are uniformly distributed over the circumference (or in a thin ring) with radius significantly exceeding the Larmor radius of particles, all particles in the LOGs perform the Larmor rotation round the cavity axis as they move along this axis.…”

“…Power P and efficiency η of output radiation as a function of current I of an electron beam for the working mode TE3,8 .…”

Terahertz Gyrotrons at IAP RAS: Status and New Designs

“…In order to enhance the selectivity of high harmonic excitation, the configuration of Large Orbit Gyrotron (LOG) with near-monoaxial (axis-encircling) electron beams are also employed [18,19]. Such beams can, in particular, be formed in guns with a cusp (reversal) of the magnetic field near the cathode [16,20].…”