查看更多>>摘要：In this study, we focus on 2-D simulation of methane dissociation using a low-temperature inductively coupled plasma reactor. This model incorporates the motions and collisions of both neutral and charged particles, including a total of 33 species (neutrals, radicals, ions, and electrons), as well as over 300 reactions (electron impact with methane, neutral-neutral, neutral-ion, and surface reactions). The results indicate a significant methane conversion rate; hydrogen production reaches 27%. The findings are highly significant and need experimental confirmation.
查看更多>>摘要：In gas discharge, the phenomenon of discharge channel bifurcation is often observed. To further understand the characteristics of channel bifurcation, this article establishes a fractal medium breakdown simulation model for the air gap of the needle plate based on fractal theory. The spatial potential is solved using the finite element method (FEM), revealing the overall morphological changes of the channel and the distribution of the electric field during discharge. Additionally, the impact of changes in the curvature radius of the needle electrode on the discharge channel distribution characteristics is analyzed and verified through experiments. The results indicate that the formation of channel branches weakens the peak electric field, and this effect diminishes as the channel branching distance increases. When the radius of curvature of the tip ranges from 50 to $200~\mu $ m, a larger radius results in a lower electric field in the channel, a wider distribution of channel branches, an increased number of branches, and a higher fractal dimension. Conversely, when the radius of curvature of the tip ranges from 200 to $500~\mu $ m, a larger radius leads to an opposite trend in the discharge channel behavior, with a decreased fractal dimension.
查看更多>>摘要：In response to the limitations of single sensors in engineering applications, this article systematically investigates the evolution process and mechanism characteristics of creeping discharge at the oil/pressboard interface under ac voltage, based on multi-sensor technology. First, a relationship between the measured amplitude and fault development time was established using multi-sensor measurement technology, revealing the variation pattern of multi-parameter signals during the creeping discharge process. Second, the mechanism characteristics of creeping discharge development process were revealed in conjunction with experimental phenomena. Finally, based on multi-parameter signals and mechanism characteristics, the discharge process is divided into three stages: slow development, rapid development, and pre-breakdown. The discharge mechanism characteristics at each stage show a significant correlation with the measured amplitude. This study provides important references for the in-depth understanding of the creeping discharge process and the synchronized detection of multi-parameter sensors.
查看更多>>摘要：This article focuses the derivation of a new evolution equation with quartic nonlinearity and its analytical solution along with dynamical features for investigating nonlinear propagation characteristics of ion-acoustic soliton (IAS) in a magnetized, rotating, relativistic plasma environment comprising of relativistic ion fluids and generalized distributed electrons, and positions. Employing the conventional reductive perturbation method, the Korteweg-de Vries (KdV) equation involving quartic nonlinearity is derived. The effect of obliqueness, relativistic streaming factor, rotational frequency, and other related plasma parameters on the nonlinear propagation characteristic is analyzed. The plasma parameters affect remarkably the propagation characteristics of IASs with the consideration of relativistic Lorentz factor (RLF) up to 20 terms rather than 2 or 3 terms. Through the implementation of a traveling wave transformation, a planar dynamical system (PDS) is rigorously formulated. The phase portrait is meticulously constructed, allowing for a comprehensive and deeply nuanced analysis of the emergent nonlinear wave phenomena inherent to the system. It is observed that even the slightest alteration in any parameter can exert a significant and abrupt influence on the propagation dynamics of IASs when approaching the super-critical threshold. The findings presented may contribute to the underlying physics in understanding soliton propagation in the astrophysical scenarios such as magnetosphere, neutron stars, dark matter halos, white dwarfs, etc. in the presence of magnetic field.
查看更多>>摘要：In this article, the design and simulation of helix slow wave structure (SWS) with dielectric support rods for Ka-band Helix-traveling wave tube (TWT) have been described. The beam-wave interaction analysis and simulation of a small helix structure have been carried out to obtain the wide bandwidth, high gain, and high power of Ka-band TWT. The dispersion and interaction impedance characteristics of helix SWS have been determined using computer simulation tool (CST)-microwave studio and experimentally measured. The design and simulation predict that helix SWS can produce >100 W output power, 55.0 dB saturated gain, 8.0 GHz bandwidth, and 30% efficiency at a 27.5–35.5 GHz frequency range. A new type of waveguide pillbox wideband output RF window has been fabricated and experimented. The stability analysis of the helix SWS also demonstrates that the loss design is a major effective for suppressing the backward oscillations in the helix TWT.
Zisis C. IoannidisKonstantinos E. OrfanidisStylianos P. Savaidis
899-906页
查看更多>>摘要：Active microwave pulse compressors (MPCs) have been under study during the last decades. Various methods are presented in the literature for the steady-state design of MPCs. On the contrary, studies on the optimization of active MPCs in time are very limited because it is rather cumbersome to simulate the time-dependent operation of the gas discharge tube (GDT). In this work, we propose a methodology to derive a time-dependent conductivity model for GDT by comparing simulation data with compressed pulses from experiments. The derived GDT model is used to demonstrate the effect of the MPC geometry on the compressed pulse shape and to show that the optimal steady-state design does not produce the highest amplitude pulse.
NETL
NSTL
IEEE