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.

ADVANCED COMPUTING TOPOLOGICAL AND DYNAMICAL INVARIANTS OF RELATIVISTIC BACKWARD-WAVE TUBE TIME SERIES IN CHAOTIC AND HYPERCHAOTIC REGIMES

The advanced results of computing the dynamical and topological invariants (correlation dimensions values, embedding, Kaplan-York dimensions, Lyapunov’s exponents, Kolmogorov entropy etc) of the dynamics time series of the relativistic backward-wave tube with accounting for dissipation and space charge field and other effects are presented for chaotic and hyperchaotic regimes. It is solved a system of equations for unidimensional relativistic electron phase and field unidimensional complex amplitude. The data obtained make more exact earlier presented preliminary data for dynamical and topological invariants of the relativistic backward-wave tube dynamics in chaotic regimes and allow to describe a scenario of transition to chaos in temporal dynamics.

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.

Huygens' Principle geometric derivation and elimination of the wake and backward wave

Huygens' Principle (1678) implies that every point on a wave front serves as a source of secondary wavelets, and the new wave front is the tangential surface to all the secondary wavelets. But two problems arise: portions of wavelets that exist outside of the new wave front combine to form a wake. Also there are two tangential surfaces so wave fronts are propagated in both the forward and backward directions. These problems have not previously been resolved by using a geometrical theory with impulsive wavelets that are in harmony with Huygens' geometrical description. Doing so would provide deeper understanding of and greater intuition into wave propagation, in addition to providing a new model for wave propagation analysis. The interpretation, developed here, of Huygens' geometrical construction shows Huygens' Principle to be correct: as for the wake, the Huygens' wavelets disappear when combined except where they contact their common tangent surfaces, the new propagating wave fronts. As for the backward wave, a source propagates both a forward wave and a backward wave when it is stationary, but it propagates only the forward wave front when it is advancing with a speed equal to the propagation speed of the wave fronts.

Determination of aortic pulse transit time based on waveform decomposition of radial pressure wave

Carotid-femoral pulse transit time (cfPTT) is a widely accepted measure of central arterial stiffness. The cfPTT is commonly calculated from two synchronized pressure waves. However, measurement of synchronized pressure waves is technically challenging. In this paper, a method of decomposing the radial pressure wave is proposed for estimating cfPTT. From the radial pressure wave alone, the pressure wave can be decomposed into forward and backward waves by fitting a double triangular flow wave. The first zero point of the second derivative of the radial pressure wave and the peak of the dicrotic segment of radial pressure wave are used as the peaks of the fitted double triangular flow wave. The correlation coefficient between the measured wave and the estimated forward and backward waves based on the decomposition of the radial pressure wave was 0.98 and 0.75, respectively. Then from the backward wave, cfPTT can be estimated. Because it has been verified that the time lag estimation based on of backward wave has strong correlation with the measured cfPTT. The corresponding regression function between the time lag estimation of backward wave and measured cfPTT is y = 0.96x + 5.50 (r = 0.77; p < 0.001). The estimated cfPTT using radial pressure wave decomposition based on the proposed double triangular flow wave is more accurate and convenient than the decomposition of the aortic pressure wave based on the triangular flow wave. The significance of this study is that arterial stiffness can be directly estimated from a noninvasively measured radial pressure wave.

Fundamental Diagram Estimation Based on Random Probe Pairs on Sub-Segments

A new statistical algorithm is proposed in this paper with the aim of estimating fundamental diagram (FD) in actual traffic and dividing the traffic state. Traditional methods mainly focus on sensor data, but this paper takes random probe pairs as research objects. First, a mathematical method is proposed by using probe pairs data and the jam density to determine the FD on a stationary segment. Second, we applied it to the near-stationary probe traffic state set through linear regression and expectation maximisation iterative algorithm, estimating the free flow speed and the backward wave speed and dividing the traffic state based on the 95% confidence interval of the estimated FD. Finally, simulation and empirical analyses are used to verify the new algorithm. The simulation analysis results show that the estimation error corresponding to the free flow speed and the backward wave speed are 1.0668 km/h and 0.0002 km/h respectively. The empirical analysis calculates the maximum capacity of the road and divides the traffic into three states (free flow state, breakdown state, and congested state), which demonstrates the accuracy and practicability of the research in this paper, and provides a reference for urban traffic monitoring and government decision-making.