Abnormal transition of the electron energy distribution with excitation of the second harmonic in low-pressure radio-frequency capacitively coupled plasmas

The self-excited second harmonic in radio-frequency capacitively coupled plasma was significantly enhanced by adjusting the external variable capacitor.At a lower pressure of 3 Pa,the excitation of the second harmonic caused an abnormal transition of the electron energy probability function,resulting in abrupt changes in the electron density and temperature.Such changes in the electron energy probability function as well as the electron density and temperature were not observed at the higher pressure of 16 Pa under similar harmonic changes.The phenomena are related to the influence of the second harmonic on stochastic heating,which is determined by both amplitude and the relative phase of the harmonics.The results suggest that the self-excited high-order harmonics must be considered in practical applications of lowpressure radio-frequency capacitively coupled plasmas.

Facile integration of an Al-rich Al_(1-x)In_(x)N photodetector on free-standing GaN by radio-frequency magnetron sputtering

Al_(1-x)In_(x)N, a Ⅲ-nitride semiconductor material, is currently of great research interest due to its remarkable physical properties and chemical stability. When the Al and In compositions are tuned, its band-gap energy varies from 0.7 eV to 6.2 eV, which shows great potential for application in photodetectors. Here, we report the fabrication and performance evaluation of integrated Al_(1-x)In_(x)N on a free-standing GaN substrate through direct radio-frequency magnetron sputtering.The optical properties of Al_(1-x)In_(x)N will be enhanced by the polarization effect of a heterostructure composed of Al_(1-x)In_(x)N and other Ⅲ-nitride materials. An Al_(1-x)In_(x)N/Ga N visible-light photodetector was prepared by semiconductor fabrication technologies such as lithography and metal deposition. The highest photoresponsivity achieved was 1.52 A·W^(-1)under 365 nm wavelength illumination and the photodetector was determined to have the composition Al0.75In0.25N/GaN.A rise time of 0.55 s was observed after transient analysis of the device. The prepared Al_(1-x)In_(x)N visible-light photodetector had a low dark current, high photoresponsivity and fast response speed. By promoting a low-cost, simple fabrication method,this study expands the application of ternary alloy Al_(1-x)In_(x)N visible-light photodetectors in optical communication.

Numerical study of the radio-frequency biased accelerating system in ion thrusters

A 2D-3V implicit immersed-finite-element particle-in-cell(IFE-PIC)model is introduced to investigate the radio-frequency(RF)self-bias accelerating system applied in the RF ion thruster.A set of holes in a two-grid system with slit apertures is simulated in Cartesian coordinates.The characteristics of the plasma plume,such as the ion density,the neutralization rate and the ion and electron current density were investigated for different RF voltage amplitudes(600-1200V)and frequencies(6-30 MHz).Furthermore,the performance of the thruster was also carefully studied.The simulation results show that a well-focused plasma beam can be formed when the voltage amplitude is larger than 900 V and the frequency exceeds the reciprocal of ion transit time(≥12 MHz)in our simulation cases.The performance of the system can be evidently improved by increasing the voltage amplitude and the frequency,and the losses of the particle and thrust are reduced correspondingly.The bulk region of the plasma beam downstream shows good quasi-neutrality,and the ions are dominant in the peripheral region when a well-focused state is achieved.The high ion density beamlet in the periphery of the ion beam is closer to the axis when the voltage amplitude is increasing,while it is expanded radially when increasing the frequency.Backstream electrons have been observed upstream,and this mainly occurs in the phase in which the electron cannot escape.

多光谱图像融合的IC器件表面缺陷检测

针对单可见光或单红外条件下的IC器件表面缺陷对比度不足,缺陷检测精度低的问题,提出多光谱图像融合的IC器件表面缺陷检测方法。针对IC器件可见光与红外图像配准中存在尺度不一致和对比度反转问题,引入拉普拉斯金字塔和特征描述符重组策略改进ORB(Oriented FAST and Rotated BRIEF)图像配准算法。在图像配准的基础上,提出NSST_VP图像融合方法,以非下采样剪切波变换(Non-Subsample Shearlet Transform, NSST)得到红外图像和已配准可见光图像的低频和高频子带,对低频子带采用视觉显著图(Visual Significance Map, VSM)加权融合规则,高频子带则采用自适应脉冲耦合神经网络(PA-Pulse Coupled Neural Network, PA-PCNN)决策融合规则,进而通过NSST逆变换得到高质量多光谱融合图像。最后,将融合图像输入YOLOv8s模型进行检测。实验结果表明,改进ORB的图像配准平均精度为87.8%,比ORB图像配准精度提高了62%,NSST_VP图像融合算法在主观视觉效果和客观评价指标上均有所提高。在缺陷检测实验中,NSST_VP融合方法的均值平均精度(mean Average Precision, mAP)达到83.15%,比单可见光、单红外缺陷图像检测的mAP分别提高了22.97%,28.31%,比双树复小波变换融合、曲线变换融合、非下采样轮廓波变换融合方法的mAP分别提高了13.14%,15.01%,20.35%。

带有左正则带的IC拟适当半群研究

文章利用富足半群上的L^(*)和R^(*)关系,得到了带有左正则带的IC拟适当半群的若干性质,特别是研究了幂等元导出的一类自同态映射。构造了半群上的一类好同余,将商半群简化为型-A半群,组建了一种具有半直积结构的AGC-系统,以此给出了带有左正则带的IC拟适当半群的一般刻画,改进了现有文献的部分结果。

IC厌氧反应器处理技术的应用研究及发展

IC厌氧反应器是第三代厌氧反应器,已广泛应用于高浓度有机废水处理。介绍了厌氧生物处理技术的特点及厌氧生物反应器的发展,重点介绍了IC厌氧反应器的构造、反应原理、特点、应用现状及发展趋势等,以期为IC厌氧反应器的应用提供参考。

基于阀切换UHPLC-IC联用技术的实验教学探索

具有阀切换的超高效液相色谱-离子色谱联用(UHPLC-IC)技术适用于同时分析含有机物和无机阴离子的样品,该联用技术简化了前处理的过程,消除了复杂基体,对无机阴离子进行富集,实现有机物和无机阴离子的同时分析,提高了色谱分析效率。将阀切换UHPLC-IC联用技术引入到本科生仪器分析实验课堂中,加深了学生对新型分析技术独特优势的理解,提高了本科生解决复杂实际问题的能力,拓宽和提升了仪器分析实验的教学内涵,有利于创新性和综合性人才的培养。

IC卡数据驱动下的公交客流分布及线路优化策略研究

为提升公交车的运营效率,研究以某市公交IC数据为基础,对公交客流进行分析,并提出基于遗传算法改进的公交线路优化模型。研究发现,该市全天公交客流出现早晚两个峰值段。工作日到节假日,客流集中地从市中心附近转变为旅游景点、公园和购物中心等地区。公交线路优化模型将某公交线路的利用率提高了15%,将乘客的平均等待时间降低了21%,有效提高了公交系统的运营效率和乘客满意度。此次研究为提升公交运营效率、改善乘客体验、优化城市交通结构、促进城市可持续发展提供重要依据和方法。

基于ICS算法的列车运动模型参数辨识

列车运动模型参数辨识对其运行控制至关重要,文章采用单质点列车模型,对运行列车进行受力分析,建立列车运动模型,并提出利用改进的布谷鸟搜索(ICS)算法对列车基本阻力参数进行辨识;基于真实的列车运行数据,对基本阻力参数辨识进行仿真分析,并基于TD3算法对参数辨识的有效性进行仿真验证。仿真结果表明,基本阻力参数辨识对列车运行控制十分必要,相对于经验参数,辨识参数下的列车基本阻力更为准确,且辨识参数下的牵引能耗有一定的降低。

基于ICA的锂电池SOH估计曲线确定方法研究

针对如何提取容量增量(IC)曲线上更有效的特征参数进行锂电池健康状态(SOH)估计问题,提出了一种基于修正的洛伦兹电压容量(RL-VC)模型。首先使用传统滤波方法对锂电池进行容量增量分析(ICA)。然后使用RL-VC模型进行对比,获得相应的特征参数并计算容量建模误差。在基于自主搭建的试验平台上获得的试验数据与开源数据集NASA中的动态数据集NCM中分别进行试验。VC容量建模的误差分别在0.23%和0.16%以内。RL-VC模型拟合的IC曲线提取的特征参数与锂电池容量高度线性相关,为后续SOH工作奠定了基础。基于RL-VC模型的IC分析方法相较于传统滤波方法,不仅在电池老化方面具有更高的鲁棒性,同时在特征参数提取方面避免了主观性和不确定性。

Numerical research of a 2D axial symmetry hybrid model for the radio-frequency ion thruster

Since the high efficiency discharge is critical to the radio-frequency ion thruster(RIT), a 2D axial symmetry hybrid model has been developed to study the plasma evolution of RIT. The fluid method and the drift energy correction of the electron energy distribution function(EEDF) are applied to the analysis of the RIT discharge. In the meantime, the PIC-MCC method is used to investigate the ion beam current extraction character for the plasma plume region. The beam current simulation results, with the hybrid model, agree well with the experimental results, and the error is lower than 11%, which shows the validity of the model. The further study shows there is an optimal ratio for the radio-frequency(RF) power and the beam current extraction power under the fixed RIT configuration. And the beam extraction efficiency will decrease when the discharge efficiency beyond a certain threshold(about 87 W). As the input parameters of the hybrid model are all the design values, it can be directly used to the optimum design for other kinds of RITs and radio-frequency ion sources.

Designing shielded radio-frequency phased-array coils for magnetic resonance imaging

In this paper, an approach to the design of shielded radio-frequency （RF） phased-array coils for magnetic resonance imaging （MRI） is proposed. The target field method is used to find current densities distributed on primary and shield coils. The stream function technique is used to discretize current densities and to obtain the winding patterns of the coils. The corresponding highly ill-conditioned integral equation is solved by the Tikhonov regularization with a penalty function related to the minimum curvature. To balance the simplicity and smoothness with the homogeneity of the magnetic field of the coll＇s winding pattern, the selection of a penalty factor is discussed in detail.

Numerical study on characteristics of radio-frequency discharge at atmospheric pressure in argon with small admixtures of oxygen

In this paper, a 1D fluid model is developed to study the characteristics of a discharge in argon with small admixtures of oxygen at atmospheric pressure. This model consists of a series of equations, including continuity equations for electrons, positive ions, negative ions and neutral particles, the energy equation, and the Poisson equation for electric potential. Special attention has been paid to the electron energy dissipation and the mechanisms of electron heating, while the admixture of oxygen is in the range of 0.1%-0.6%. It is found that when the oxygen-to-argon ratio grows, the discharge is obviously divided into three stages： electron growth, electron reduction and the electron remaining unchanged. Furthermore, the cycle-averaged electric field, electron temperature, electron Ohmic heating, electron collisionless heating, electron energy dissipation and the net electron production are also studied in detail, and when the oxygen-to- argon ratio is relatively larger （R = 0.6%）, double value peaks of electron Ohmic heating appear in the sheath. According to the results of the numerical simulation, various oxygen-to-argon ratios result in different amounts of electron energy dissipation and electron heating.

Hemodynamic changes in hepatic cancer before and after cluster electrode radio-frequency ablation

Objective: To evaluate the hemodynamic changes of hepatic artery (HA), portal vein (PV) and tumors in hepatic cancer patients treated by cluster electrode radio-frequency ablation with the aid of color Doppler flow imaging (CDFI). Methods: The hemodynamic changes of HA, PV and 42 tumors in 30 cases of hepatic cancer were investi- gated by CDFI one week before and after cluster e- lectrode radio-frequency ablation. Results: One week after radio-frequency ablation, the velocity of HA decreased (P<0.05), but the dia- meter and velocity of PV unchanged. Before radio- frequency ablation, blood signals were observed in 35 cancer nodes (83.0 % of all 42 nodes). After radio- frequency ablation, blood signals were reduced in 15 nodes and disappeared in 14 nodes. Early investiga- tion implied that the decrease of blood supply was parallel with the reduction of node size. However, the outcome in case of huge nodes with double blood supply was not as promising as those small nodes. Conclusion: CDFI is useful to assess blood supply in ablation of hepatic cancer by using cluster electrode radio-frequency therapy.

Applications of cold atmospheric plasmas(CAPs)in agriculture:a brief review and the novel development of a radio-frequency CAP jet generator for plant mutation

Cold atmospheric plasmas(CAPs)have shown great applicability in agriculture.Many kinds of CAP sources have been studied in agricultural applications to promote plant growth and cure plant diseases.We briefly review the state-of-the-art stimulating effects of atmospheric-pressure dielectricbarrier-discharge(AP-DBD)plasmas,after the direct or indirect treatment of plants for growth promotion and disease control.We then discuss the special demands on the characteristics of the CAP sources for their applications in plant mutation breeding.An atmospheric and room temperature plasma(ARTP)jet generator with a large plasma irradiation area,a high enough concentration of chemically reactive species and a low gas temperature is designed for direct plant mutagenesis.Experimental measurements of the electrical,thermal and optical features of the ARTP generator are conducted.Then,an ARTP-P(ARTP for plant mutagenesis)mutation breeding machine is developed,and a typical case of plant mutation breeding by the ARTP-P mutation machine is presented using Coreopsis tinctoria Nutt.seeds.Physical and agricultural experiments show that the newly-developed ARTP-P mutation breeding machine with a large irradiation area can generate uniform CAP jets with high concentrations of chemically reactive species and mild gas temperatures,and have signiflcant mutagenesis effects on the Coreopsis tinctoria Nutt.seeds.The ARTP-P mutation breeding machine may provide a platform for systematic studies on mutation mechanisms and results for various plant seeds under different operating conditions in future research.

Simulation of radio-frequency atmospheric pressure glow discharge in γ mode

The existence of two diffe1：ent discharge modes has been verified in an rf （radio-frequency） atmospheric pressure glow discharge （APGD） by Shi [J. Appl. Phys. 97, 023306 （2005）]. In the first mode, referred to as a mode, the discharge current density is relatively low and the bulk plasma electrons acquire the energy due to the sheath expansion. In the second mode, termed γ mode, the discharge current density is relatively high, the secondary electrons emitted by cathodc under ion bombardment in the cathode sheath region play an important role in sustaining the discharge. In this paper, a one-dimensional self-consistent fluid model for rf APGDs is used to simulate the discharge mechanisms in the mode in helium discharge between two parallel metallic planar electrodes. The results show that as the applied voltage increases, the discharge current becomes greater and the plasma density correspondingly increases, consequentially the discharge transits from the a mode into the γ mode. The high collisionality of the APGD plasma results in significant drop of discharge potential across the sheath region, and the electron Joule heating and the electron collisional energy loss reach their maxima in the region. The validity of the simulation is checked with the available experimental and numerical data.

Influence of magnetic filter field on the radio-frequency negative hydrogen ion source of neutral beam injector for China Fusion Engineering Test Reactor

In the design of negative hydrogen ion sources,a magnetic filter field of tens of Gauss at the expansion region is essential to reduce the electron temperature,which usually results in a magnetic field of around 10 Gauss in the driver region,destabilizing the discharge.The magnetic shield technique is proposed in this work to reduce the magnetic field in the driver region and improve the discharge characteristics.In this paper,a three-dimensional fluid model is developed within COMSOL to study the influence of the magnetic shield on the generation and transport of plasmas in the negative hydrogen ion source.It is found that when the magnetic shield material is applied at the interface of the expansion region and the driver region,the electron density can be effectively increased.For instance,the maximum of the electron density is 6.7×10^(17)m^(-3)in the case without the magnetic shield,and the value increases to 9.4×10^(17)m^(-3)when the magnetic shield is introduced.

基于项目学习的IC设计类专业实践教学体系优化探索

文章首先阐述了基于项目学习的IC设计类专业实践教学体系优化原则,然后从明确教学目标、优化实践教学内容、优化教学方法、优化教学评价方式四个方面论述了基于项目学习的IC设计类专业实践教学体系优化策略,最后总结了基于项目学习的IC设计类专业实践教学体系优化成效。

Characterization of La-doped xBiInO_3(1-x)PbTiO_3 Piezoelectric Films Deposited by the Radio-Frequency Magnetron Sputtering Method

La-doped and undoped xBiIn03-（1 - x）PbTi03 （BI-PT） thin films are deposited on （101）SrRuO3/（lOO）Pt/（lO0） MgO substrates by the rf-magnetron sputtering method. The structures of the films are characterized by XRD and SEM, and the results indicate that the thin films are grown with mainly （100） oriented and columnar structures. The ferroelectricity and piezoelectricity of the BI-PT films are also measured, and the measured results illustrate that both performances are effectively improved by the La-doping with suitable concentrations. These results will open up wide potential applications of the films in electronic devices.

Radio-frequency magnetron sputtered thin-film La_(0.5)Sr_(0.5)Co_(0.95)Nb_(0.05)O_(3-δ) perovskite electrodes for intermediate temperature symmetric solid oxide fuel cell(IT-SSOFC)

The present work explores the application of La_(0.5)Sr_(0.5)Co_(0.95)Nb_(0.05)O_(3-δ)(LSCNO)perovskite as electrode material for the symmetric solid oxide fuel cell.Symmetric solid oxide fuel cells of thin-film LSCNO electrodes were prepared to study the oxygen reduction reaction at intermediate temperature.The Rietveld refinement of syn-thesized material shows a hexagonal structure with the R-3c space group of the prepared perovskite material.Lattice parameter and fractional coordinates were utilized to calculate the oxygen ion diffusion coefficient for molecular dynamic simulation.At 973 K,the oxygen ion diffusion of LSCNO was 1.407×10^(-8)cm^(2)s^(-1) higher by order of one magnitude than that of the La_(0.5)Sr_(0.5)Co_(0.95)Nb_(0.05)O_(3-δ)(7.751×10^(-9)cm^(2)^(-1)).The results suggest that the Nb doping provide the structural stability which improves oxygen anion diffusion.The enhanced structural stability was analysed by the thermal expansion coefficient calculated experimentally and from molecular dynamics simulations.Furthermore,the density functional theory calculation revealed the role of Nb dopant for oxygen vacancy formation energy at Sr-0 and La-O planes is lower than the undoped structure.To understand the rate-limiting process for sluggish oxygen diffusion kinetics,80 nm and 40 nm thin films were fabricated using radio frequency magnetron sputtering on gadolinium doped ceria electrolyte substrate.The impedance was observed to increase with an increasing thickness,suggesting the bulk diffusion as a rate-limiting step for oxygen ion diffu-sion.The electrochemical performance was analysed for the thin-flm symmetric solid oxide fuel cell,which achieved a peak power density of 390 mW cm^(-2) at 1.02 V in the presence of H_(2) fuel on the anode side and air on the cathode side.