Specific features of the development of a high-stability continuous-wave gyrotron operated at the second harmonicwith a working frequency OF 258 GHz

Abstract

We consider specific features of the development of a continuous-wave 258 GHz gyrotron operated at the second gyrofrequency harmonic, which are related to ensuring of high stability of its output parameters. The requirements to accuracy of manufacture of the cavity and adjustment of the electron beam are evaluated, as well as the necessary parameters of the power sources of the gyrotron complex, which should maintain the required level and stability of the generated power and frequency. The influence of the effect of spurious-mode reflection from the output window of the gyrotron is studied.

Experimental study of a continuous-wave high-stability second-harmonic gyrotron for spectroscopy of dynamically polarized nuclei

“…The measurements of the long-term relative instability of the power and frequency of the gyrotron, performed at the same institute, showed that they did not exceed 1% and 5·10 −6 , respectively. It was established experimentally that varying the cavity temperature by controlling the cooling-water temperature allows one to tune the generation frequency within some limits at a rate of 4 Mhz/ • C. This agrees well with the theoretical estimates [7].…”

“…In particular, it was shown that for an accelerating voltage of 13-15 kV and an electron beam current of 0.2-0.5, the output power could reach 0.1-0.3 kW. In [7], the issues of ensuring high stability of such a gyrotron were discussed. In [8], the method and results of the development of the system for the formation of a helical electron beam were presented.…”

“…The cavity is coupled with an output waveguide 20 mm in diameter via a smoothly profiled transition, which ensures comparatively low parasitic transformation of the operating mode. The cavity is thermally insulated from the collector and has a separate water-cooling system to ensure the required temperature stability [7]. The collector of a gyrotron electron beam 20 mm in diameter is integrated with the output waveguide and has a water cooling system.…”

Influence of the axial misalignment of the electron beam and the cavity on the gyrotron parameters

“…The authors of [11][12][13] considered the issues of designing and optimizing a high-stability gyrotron with an output frequency of 258 GHz to be operated in the continuous-wave regime at the second gyrotronfrequency harmonic. This tube is currently a component of the dynamic nuclear polarization complex for magnetoresonance spectroscopy studies at the Institut für Biophysikalische Chemie, Goethe Universität, Frankfurt-am-Main, Germany.…”

Generation of high power sub-terahertz radiation from a gyrotron with second harmonic oscillation

“…7,[22][23][24] Recently, development of SH gyrotrons has been intensified in anticipation of new applications. [25][26][27] However, the powers of these gyrotrons are in the range from tens of watts to kilo watts. The maximum power so far realized in the sub-THz band with SH gyrotron was around 20 kW.…”