Powerful continuous-wave sub-terahertz electron maser operating at the 3rd cyclotron harmonic

Abstract

Coherent subterahertz radiation is achieved in an electron cyclotron maser (large-orbit gyrotron configuration) operating at a higher cyclotron harmonic in the continuous-wave generation regime. This auto-oscillator is based on the use of a gun with a magnetic field cusp and a section for adiabatic magnetic compression with a factor of 1000, forming a 30 keV/0.7 A axis-encircling electron beam in a magnetic field of 5 T. A stable single-mode generation is achieved in the case of operation at the third and second cyclotron harmonics at frequencies of 0.394 THz and 0.267 THz with radiation powers of 0.37 kW and 0.9 kW, respectively.

Russian Gyrotrons: Achievements and Trends

“…This generator is used successfully for obtaining a terahertz discharge in gases in the studies aimed at creating a point source of extreme UV radiation. The second and third harmonic CW LOG based on 5 T in-house made cryomagnet successfully realized and demonstrated power level close to 1 kW at the frequencies up to 0.4 THz [38].…”

The Gyrotrons as Promising Radiation Sources for THz Sensing and Imaging

“…Although the latter approach is hindered by severe mode competition and significantly lower efficiency, there is remarkable progress in the development of gyrotrons operating at high harmonics. They include second-harmonic conventional gyrotrons (utilizing helical electron beams with off-axis orbits) [27][28][29][30][31][32] as well as tubes based on advanced concepts such as LOG (large-orbit gyrotrons with axis-encircling aka uniaxial electron beams) [33][34][35] and double-beam gyrotron [36]. The highest frequencies achieved by the gyrotrons have already passed the symbolic threshold value of 1 THz.…”

Planar Bragg Reflectors for Frequency-Tunable Sub-Terahertz Gyrotrons

“…From the point of view of such characteristics as high generation frequency and output power, compactness, the ability to provide long-pulse and continuous generation modes, narrow-band output signal, and sub-THz gyrotrons [12][13][14][15][16][17][18][19][20][21][22][23][24][25] are the most attractive for such applications. However, a principal disadvantage of traditional gyrotrons is that the use of high-Q, close to the cut-off value in axial modes with open cavities present as operating waves, which makes broadband frequency tuning difficult.…”