Релятивистская лампа обратной волны с продольно-щелевым дифракционным выходом

The results of experimental studies evaluating the influence of longitudinal slits in a conical diffraction outlet, combined with an electron collector, of a 10 GHz relativistic BWO (Backward-Wave Oscillator) with an operating mode TM01 are presented. It has been shown experimentally that replacing a solid conical waveguide with a similar longitudinal-slotted waveguide has little effect on the performance of the BWO. The use of a longitudinally slotted diffraction outlet instead of a continuous one makes it possible to reduce the volume of plasma and microparticles formed on the diffraction outlet surface under the action of an electron beam, and to improve their adsorption and removal.

A novel self-injection relativistic backward wave oscillator

A novel self-injection relativistic backward wave oscillator (RBWO) has been proposed. By introducing a self-injection path into the RBWO, a small portion of the energy in the reflector can be coupled to the upstream of the reflector, and then the formed electric field in the self-injection path region can pre-modulate the passing electron beam, to promote a frequency-locking oscillation of the electron beam. The pre-modulated electron beam can be expected to enhance the beam-wave interaction and suppress parasitic mode oscillation, which is beneficial for maintaining the dominant role of the operating mode. The proposed self-injection RBWO shows great potential for improving the conversion efficiency and pulse duration time. Through particle-in-cell simulation, a microwave with a power of 10.6 GW is obtained, when the beam voltage is 1.08 MeV, and the beam current is 18.6 kA. The conversion efficiency is 53%.

Stabilization of the backward wave oscillator frequency for operation with high quality resonators

This article describes the performance of a backward wave oscillator, stabilized with phase locked loop. The backward wave oscillator is locked to the frequency of a direct digital synthesizer using an automatic phase locked loop. The direct digital synthesizer is playing the role of tuning part in the suggested frequency synthesizer. Mathematical evaluations of the stability, phase noise and locking speed of the suggested frequency synthesizer are obtained. The optimization technique of frequency synthesizers parameters is presented. This allows to get the maximum response speed and the lowest phase noise and level of spurious with fine tuning (less than 1 Hz). It was shown that the order and type of loop filter in the frequency synthesizer will affect simultaneously the response speed, phase noise and spurious level. The results of this paper shows that the frequency synthesizer can be used in small samples properties measurement using open resonators.

Two-dimensional THz reflectometry of a periodic structure obtained by additive technology

This paper considers the development and application of a system of reflectometry for the analysis of the homogeneity of structures manufactured by additive technologies. A system of reflectometry based on a backward wave oscillator, a two-dimensional object positioning system and an optoacoustic detector (Goley cell) is described. The results of reflectometry of the hexagonal periodic structure of cells based on acrylonitrile butadiene styrene at a wavelength of 343 microns are presented.

Simulation Investigations of High Power Overmoded Relativistic Backward Wave Oscillator with Trapezoidal Resonant Reflector

An S-band high power relativistic backward wave oscillator using a trapezoidal resonant reflector and overmoded slow-wave structure is demonstrated by finite difference time domain based Particle-In-Cell code. The trapezoidal resonant reflector and slow-wave structure are chosen to improve the RBWO power handing capability to gigawatt (GW). The Trapezoidal resonant reflector enhances the pre-modulation during electron beam propagation, thus increasing the generated RF signal overall efficiency and coherency. The particle-in-cell simulation generated an RF output power ~5.4 GW in TM01 mode at ~3.6 GHz in a 2.0 T magnetic field and developed a 13.5 kA current for a 1.2 MV DC cathode voltage. The power conversion efficiency is achieved as ~33 %. Further, the influence of different design parameters on frequency, RF output power, and efficiency are analysed through Particle-In-Cell simulations.