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This letter proposed a combined susceptibility diagram, applicable to investigating and differentiating the inherent mechanism of multipactor in dielectric-loaded microwave devices. This susceptibility diagram consists of average secondary emission yield on the dielectric surface and both the surfaces. Using this diagram, we predict the electron multiplication mechanism in the partially dielectric-loaded parallel-plate waveguide. It is found that the multipactor extinguishing only occurs for a low multipaction rate, while the saturation occurs for a higher multipaction rate. To verify its validity, the dynamic evolution of multipactor is investigated by electrostatic particle-in-cell. A good agreement between simulations and prediction results has been achieved. This susceptibility diagram thus constructed can provide a guidance to clearly identify the condition for multipactor extinguishing or saturation. [ABSTRACT FROM AUTHOR]

This paper proposes a theoretical model for the single-surface multipactor on a dielectric. We consider the combined effects of the normal cumulative electric field, the normal and tangential radio frequency (RF) electric fields, as well as the tangential external direct current (DC) magnetic field and study the suppression effect of the tangential external DC magnetic field on the resonant multipactor. Kinetic properties of the electron and the resonant multipactor condition with no tangential external DC magnetic field are derived by analytical calculations. The flight time of the electron is analyzed profoundly by considering different values of the electron's initial energy, the amplitude ratio between the normal cumulative electric field and the normal RF electric field, and the tangential external DC magnetic field. Our results demonstrate that the tangential external DC magnetic field can decrease the flight time, and hence, the resonant multipactor can be suppressed or mitigated effectively by the tangential external DC magnetic field. The flight time of the electron shows a decreasing trend as the electron's initial energy increases, and the amplitude ratio between the normal cumulative electric field and the normal RF electric field decreases. The suppression effect of the tangential external DC magnetic field on the resonant multipactor can be much stronger when the amplitude ratio between the normal cumulative electric field and the normal RF electric field becomes larger. The resonant multipactor suppressing is also relevant to the amplitude ratio and the initial phase difference between the tangential and normal RF electric fields. [ABSTRACT FROM AUTHOR]

The analytical description of dielectric multipactors requires an accurate physical model. In this article, a nonstationary statistical theory for the analysis of single-surface dielectric multipactors is established by defining an emission-to-emission transition rate and involving all the probability densities related to the emitted secondary electrons. Under the same conditions, the fluctuation of electrons in the evolution process of dielectric multipactors was calculated by the proposed theory and simulated by a commercial particle simulation tool developed based on the Monte Carlo analysis. The calculated results comply well with the simulated ones. Our results also indicated that to obtain an adequate accuracy, at least two random variables, the emission velocity and zenith angle, need to be considered. [ABSTRACT FROM AUTHOR]

The aim of this article is to establish a general and practical analytical model of the one-sided multipactor on a dielectric of a metal surface and analyze the resonant multipactor effect for the recent growing interest in spacecrafts. A theoretical multipactor model involving a normal static electric field, a radio frequency (RF) electric field with both tangential and normal components, and the influence of the desorption gas is proposed. The kinetic properties and the resonant condition of the electron are studied by analytical calculations. The results show that the transit time of the electron decreases with the increase in the normal static electric field and the pressure of the desorption gas. The emission phase of the electron is the paramount factor that has a direct influence on the occurrence of the resonant multipactor. If the resonant multipactor effect could appear, the emission phase of the electron should be larger than a critical phase, and the ratio between the amplitude of the normal component of the RF electric field and the normal static electric field should be larger than a specific value as well. [ABSTRACT FROM AUTHOR]

Charging effects of dielectric due to space electron beam irradiation have a huge impact on spacecraft. To understand charging equilibrium characteristics of dielectric under electron beam irradiation, in this paper, we present a novel numerical simulation method for analyzing the secondary electron yield (SEY) based on a charging balance mode. We used the Mott scattering model and the Penn dielectric function (PDF) model to calculate the collisions between incident electrons and material the atoms of material. For internal charge transport, we considered the processes of drift, diffusion, trapping, and neutralization. These were calculated with a finite-difference time-domain (FDTD) method. Based on mechanisms of import–export dynamic charge evolution, charging balance can be categorized into three modes: SE mode, leakage (LE) mode, and cooperation (CO) mode (a combination of the two). In most situations, the SE mode corresponds to the surface charging state, while the LE mode always corresponds to deep charging states. Shortening the distance of free charge transport, a thinner sample is more likely to present as LE mode. Although the surface potential can be enhanced by monotonously increasing the thickness, the total internal charge quantity approaches a local maximum with thickness because of a charging balance mode transformation. In addition, with a larger average density of carriers in the LE mode, the material conductivity is enhanced and the dielectric loss tends to be larger at low frequencies (<103 Hz). The charging balance mode method in this study can also be appropriate to the analyses of altering irradiation parameters and materials intrinsic parameters. [ABSTRACT FROM AUTHOR]

The underlying mechanisms of multipactor between dielectric and metal and the discharge threshold of practical dielectric components have been investigated numerically and experimentally in this paper. The reduction in secondary electron yield (SEY) and the change in surface condition are achieved using the microstructure processing technology on both of ferrite dielectric and metal. Combined with the electromagnetic particle-in-cell method, the SEY model fit with the experimental data is utilized to simulate multipactor in three groups of ferrite circulators with different surface conditions. Simulation and experimental results demonstrate that the multipactor threshold of the circulator is increased by a factor of 2 through the SEY reduction on the ferrite and is increased by a factor of more than 8, from 380 W to more than 3400 W, through the SEY reduction on both of the ferrite and the metal. Different multipactor discharge mechanisms, including two-side multipactor with positive charge accumulation, singe-side multipactor with negative charge accumulation, and multipactor suppression effect, exist in circulators with the same physical structure and different surface conditions. [ABSTRACT FROM AUTHOR]

A uniform time-domain finite integration technique (TDFIT) is presented. Unlike the previously published conformal methods, the proposed TDFIT can be used to model both perfect electrical conductors and dielectric objects. A simple and fast extraction of conformal information is developed according to a general and analytical function to improve the efficiency of the uniform TDFIT. Numerical results are presented to verify the accuracy of the method, with three examples covering scattering and radiation applications. [ABSTRACT FROM AUTHOR]