Boris Kuz'mich Skrynnik

On the feedback in the Smith-Purcell experiment

Refers to the well understood mm-wave region with a standard accelerating voltage 3-5 kV. The positive feedback is held not on the zeroth but minus first space harmonic of the grating surface wave, i.e. the modulated electron beam is self-excited in BWT mode at /spl lambda//spl ap/ 11 mm. The high time harmonics of the modulated electron beam are radiated under certain conditions nearly orthogonal to it as fast (volume) waves. Just an experimental verification of the near-millimeter radiation of the fast (volume) waves not from externally modulated but self-excited surface eigenwave mode electron beam is proof that the coherent radiation of light on fast (volume) waves is due to the nonrecognized Smith-Purcell beam automodulation by infrared surface eigenwaves of the planar reflecting grating.

Diffraction radiation oscillator with resonant groove on the mirror

Experimental results of diffraction radiation oscillator investigation in the 5-mm wave range are presented. In order to improve the DRO output characteristics the step resonant obstacle as a groove on the OR mirror is applied. The DRO frequency tuning range was 42-64 GHz under the output level up to 5 Watt.

A study of the diffraction radiation oscillator for narrowing the diffraction structure

The diffraction radiation oscillator (DRO) differs from the orotron in that the DRO diffraction structure covers only a part of the plane (spherical) mirror rather than the full mirror surface as the orotron grating does. A narrow diffraction structure is easier in fabrication, it allows us to increase the loaded Q of the DRO oscillatory circuit and enhance efficiency of the diffraction radiation feed to the open resonator and it also changes the excited mode content. Considering that the chosen (optimized) width of the DRO periodic structure is more than twice that of the electron beam, we have a good possibility for reducing the grating ohmic loss, which amounts to a half of the DRO total loss, by some more grating narrowing. The problem, however, is that a decrease in grating width together with narrowing the grating-accommodating canal degrades the DRO performance (the combined tuning range is displaced, the starting current rises), and this takes place in spite of the loaded Q enhancement. In this work, our concern will be with the DRO whose diffraction structure about 4-mm. wide is almost equal to the electron beam width, which is about 3.8 mm. The periodic structure is put into a roomy, 10-mm wide canal. The canal is such as to accommodate the optimum-width grating in the previous DRO modification, and it offers more room than the present grating size requires.

Design and study of the high-efficiency diffraction radiation oscillator

The main achievements in the development of the diffraction radiation oscillator (DRO) are brought together; the IRE NASU have created various DRO versions which at the accelerating voltage of 2.5 - 4.0 kV continuously span the whole mm wave region. With the feed under 500 W, the output power level varies from less than 1 W in the short-wave part of the mm wave region to tens of watts in the long-wave part. We seek to report the progress made during the last three years in further understanding DRO physics, in the extension of combined (mechanical and electronic) frequency tuning and in the enhancement of the DRO interaction efficiency.

Enhancement of interaction efficiency in diffraction radiation oscillator

The output characteristics of the diffraction radiation oscillator with small-volume open resonator are examined.

High stability millimeter-wave vector analyzer

Summary for only given. A number of microwave plasma diagnostic techniques working in the short part of the millimeter wave band require high stability sources with output power about 0.5-1 Watt and the high resolution receiving system. New opportunities for the collective scattering and interferometry can provide a new type of electrovacuum device-Diffraction Radiation Oscillators (DRO) and locked measuring systems based on the DROs. The high stability Vector Analyzer of the superheterodyne type with coherent heterodyning was developed and investigated in a short part of the mm band. The source of the band is the DRO locked in by PLL-system with frequency standard. That allowed increase of the long-time instability up to 5/spl times/10/sub -10/.