Excitation of orotron oscillations at the doubled frequency of a surface wave

Abstract

We study theoretically an electron frequency self-multiplier in which a surface mode of a periodic system is self-excited at a low frequency for a comparatively low current. The electron bunches, which appear as a result of this, excite the volume mode of an open resonator at the doubled frequency (coherent Smith-Purcell radiation). The open-resonator scheme allows one to obtain the higher power and coherence degree of radiation compared with the presently popular frequency multiplication scheme with an open periodic system (diffraction grating). The weakly relativistic and relativistic variants of the multipliers with a two-mirror open resonator designed for obtaining a high-power coherent radiation in the short-wavelength part of the millimeter and submillimeter ranges are studied numerically. The developed approach can also be used for designing high-power frequency multipliers on the basis of an array of nonlinear solid-state elements.

Smith–Purcell frequency multiplier with synchronization of radiation from a wide electron beam

“…2͒, the mode of the open cavity operates at the second harmonic of the frequency 1 of the -type surface mode. 17 Such a situation was observed in our recent experiment with a relativistic orotron. 19 While at the voltage of 400 kV the planned orotron generation take place, at the lower voltage ͑U = 350 kV͒ high-power radiation with a frequency of 79 GHz ͑which coincides with the calculated wavelength of the surface -mode͒ was obtained with a mixture of 158 GHz radiation.…”

“…It is clear that a significantly higher power and a better selectivity can be obtained using an additional cavity for Smith-Purcell radiation. 17,18 In this case, the cavity can provide an effective feedback for the wave at a definite frequency harmonic, which gives rise to induced high-frequency radiation. In this paper, we show that the selective two-mirror open cavity can provide not only the stimulated nature of the frequency-multiplied Smith-Purcell radiation, 17 but also the synchronization of radiation from a wide electron beam.…”

Smith-Purcell Based Terahertz Frequency Multiplier: Three Dimensional Analysis

“…This phenomenon is considered to be one of the most interesting methods of generating sub-millimetre waves mainly in THz realm [9][10][11][12][13][14][15][16]. At frequency harmonics of the mentioned surface waves, in which the electron bunches advance, spontaneous SPR develops.…”

“…As discussed in the most of theoretical studies [19] and in experimental ones [21], SPR power is still very low which its origin seems to be from its spontaneous nature. However if an additional cavity is used, one can harness higher power and better selectivity [10]. Due to non-relativistic nature of the device, it neither requires a high operational voltage nor a large focusing magnet.…”

Experimental demonstration of Smith–Purcell radiation enhancement by frequency multiplication in open cavity

“…In contrast to the numerous papers [9][10][11][12][13][14][15][16][17][18] where the open grating itself is considered as an electrodynamic system of such multipliers, we propose to use for such a device a two-mirror open cavity similar to the orotron one, which provides effective feedback for a definite frequency harmonic. 8,19,20 In the proposed regime ͓Fig. 1͑a͔͒, the orotron periodic structure serves simultaneously as a cavity for low-frequency surface ͑evanescent͒ waves.…”