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Effect of surface modification on the radiation stability of diamond ohmic contacts

Chinese Physics B 2024年第2期33卷 444-448页

作者：牟恋希赵上熳王鹏原晓芦刘金龙朱志甫陈良贤魏俊俊欧阳晓平李成明 Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China School of Mechanical Engineering University of Science and Technology BeijingBeijing 100083China School of Information Engineering Zhengzhou University of TechnologyZhengzhou 450044China State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Northwest Institute of Nuclear TechnologyXi’an 710024China

The ohmic contact interface between diamond and metal is essential for the application of diamond *** modification can significantly affect the contact performance and eliminate the interface polarization ***,the radiation stability of a diamond detector is also sensitive to surface *** this work,the influence of surface modification technology on a diamond ohmic contact under high-energy radiation was *** radiation,the specific contact resistivities(ρc)between Ti/Pt/Au-hydrogen-terminated diamond(H-diamond)and Ti/Pt/Au-oxygenterminated diamond(O-diamond)were 2.0×10^(-4)W·cm^(2) and 4.3×10^(-3)Wcm^(2),*** 10 MeV electron radiation,the ρc of Ti/Pt/Au H-diamond and Ti/Pt/Au O-diamond were 5.3×10^(-3)W·cm^(2)and 9.1×10^(-3)W·cm^(2),*** rates of change of ρc of H-diamond and O-diamond after radiation were 2550%and 112%,*** electron radiation promotes bond reconstruction of the diamond surface,resulting in an increase in ρc.

关键词： single crystal diamond ohmic contact surface modification electron radiation

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The lifetime of a high-current triggered vacuum switch with multi-gap

The lifetime of a high-current triggered vacuum switch with ...

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International Symposium on Discharges and Electrical Insulation in Vacuum

作者： Zhengyang Zhou Ling Dai Yanzhao Wang Fuchang Lin State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

Triggered vacuum switch (TVS) synthesizes the merits of spark gap and vacuum technology. A TVS sample with multi-gap is described in this paper, in which the main electrode is made up of spatially interleaved rods of opposite polarity on a ring. Three pairs of rods are adopted, which can form six main gaps, promoting the high current carrying ability evidently. Due to hundreds of high current pulses, the influence of vacuum arc to the trigger pin and main electrode is inevitable, leading to the termination of lifetime of TVS, especially in the erosion of trigger pin and arc deposition on the trigger surface. In this paper, the major influence factors of lifetime are analyzed and it is concluded that the main current arc is the key factor to determine the lifetime of TVS. As well the change of trigger voltage, trigger resistance and trigger delay will predict the termination of TVS lifetime.

关键词： Surface treatment Surface resistance Electrodes Switches Vacuum arcs Delay

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A Preliminary Look at the Unity of Frequency Support for Grid-Following and Grid-Forming Wind Turbines

A Preliminary Look at the Unity of Frequency Support for Gri...

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Electrical engineering (CIYCEE), IEEE China International Youth Conference on

作者： Hongyu Zhou Wei Yao Qihang Zong Jinyu Wen State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (数字)9798331530174

ISBN: (纸本)9798331530181

Grid-connected wind turbines for frequency support of the grid is conducive to improving the grid frequency security level. Grid-following (GFL) converters and gridforming (GFM) converters are two important types of equipment to support renewable energy integration into the grid. Both GFM and GFL have a variety of different control strategies when performing frequency support. Clarifying the relationship be-tween different strategies of GFM and GFL when performing frequency support will provide guidance for renewable energy frequency support. In this paper, four levels of frequency support uniformity are first established at the generation unit level. (1) The governor and damping branch of the virtual synchronous generator (VSG) control based GFM converter are unified. (2) The VSG based GFM and the droop based GFM are unified. (3) Integrated inertial control based GFL and droop based GFL are unified. Finally, the theoretical analysis is synthetically verified by MATLAB/Simulink simulation platform.

关键词： Damping Renewable energy sources Grid following Frequency conversion Synchronous generators Wind turbines Security MATLAB Frequency control Grid forming

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A Denoising Scheme for Core Earth Current of Power Transformers

A Denoising Scheme for Core Earth Current of Power Transform...

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Electrical engineering and Control Science (IC2ECS), International Conference on

作者： Zhe Wu Zhaohui Li State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

The core earth current (CEC) is composed of a variety of components, some of which can reflect the health status of power transformers, such as the power frequency and its harmonic components can reflect power transformer core grounding state and core saturation degree, and some pulse components can reflect partial discharge in power transformers. Some high-frequency components can reflect the external shock (very fast transient overvoltage, lighting, etc.) suffered by power transformers. There are also some noise components introduced by ambient environment and measurement system. The existing CEC monitoring devices focus on part of the components, such as the power frequency and its harmonic components or partial discharge pulse component. Both devices are difficult to catch all anomalies in CEC. A current transformer (10Hz-200kHz) is used to sense CEC continuously to catch all abnormal waveforms in CEC. In order to extract the pulse components in CEC, a denoising scheme based on mathematical morphological (MM) filter and wavelet shrinkage is devoted. MM filter can suppress the low frequency component while maintaining the integrity of pulse components. For the purpose of filtering out the white noise in the signal and preserve the complete pulse waveform as much as possible, a new wavelet selection method that the optimum wavelet at each level is selected as the one maximizing the energy ratio of detailed coefficients beside and inside the range formed by the threshold is devoted. Simulated data and field data are used to compare several different wavelet selection methods, and the experimental results show that the pulse distortion extracted by this method is smaller than other methods.

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Study of multiphase modular stator SPM based on phase variable model

Study of multiphase modular stator SPM based on phase variab...

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International Conference on Electrical Machines and Systems (ICEMS)

作者： Xi Peng Libing Zhou Jin Wang Huilin Kang State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781479951635

Multiphase modular stator surface-mounted permanent magnet machine(MSPM) features non-sinusoidal back electromotive force. As a result, the d-q model of MSPM is not accurate enough due to the ignorance of space harmonics. Phase variable model is able to be used to perform simulation of electric machine with same accuracy level as the full finite element(FE) model with much less simulation time. This paper aims to figure out the difference between the MSPM with conventional permanent magnet(PM) and shaped PM, and the phase variable model is adopted. Rotor-position-dependent variables including inductance, back electromotive force and cogging torque are obtained from FE model. Apparent inductance and incremental inductance are respectively applied to take the saturation effect of the ferromagnetic materials into account. Simulation with phase variable model of MSPM is performed using SIMULINK, and the results show that the MSPM with shaped PM has a better torque characteristic.

关键词： Torque Inductance Harmonic analysis Forging Windings Integrated circuit modeling Stators

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Complex Permittivity Extraction of Vacuum Windows for a Compact FEL-THz Source

Complex Permittivity Extraction of Vacuum Windows for a Comp...

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International Conference on Infrared and Millimeter Waves

作者： Jing Ding Zhengya Yin Huiting Xia Lei Cao State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (数字)9781728166209

ISBN: (纸本)9781728166216

Exact calculation of the power transmittance requires optical parameters of terahertz (THz) vacuum windows, widely used in the optical path in a vacuum electron system, such as the free electron laser (FEL) THz source. A method for extracting optical parameters of thick vacuum window materials based on THz-TDS was utilized for the determination of emitted power from the down-stream mirror of a compact FEL-THz facility at Huazhong University of Science and technology (HUST). The real and imaginary part of permittivity for TPX and HRSi were extracted in a wide frequency range from 0.5 to 4.5 THz by the transmission-mode TDS measurement.

关键词： Vacuum systems Stimulated emission Power lasers Optical imaging Electron optics Frequency measurement Permittivity

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The optimal allocation of D-SMES for enhancing transient stability of power system

The optimal allocation of D-SMES for enhancing transient sta...

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IEEE Workshop on advanced Research and technology in Industry Applications (WARTIA)

作者： Shu Wang Yuejin Tang Jing Shi Yajun Xia Kang Gong State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781479969906

This paper proposes a method to determine the optimal allocation of distributed superconducting magnetic energy storage system (D-SMES) capacity for enhancing the transient stability of power system. A kind of multi-objective evolutionary algorithm (MOEA) is adopted to find the optimal allocation when a certain number of D-SMES devices are deployed in the certain location of the system. The index of trajectory of generator speed after large disturbance is adopted to indicate the stability of power system. Then, the simulation with the Western Systems Coordinating Council (WSCC) three-machine nine-bus power system is evaluated.

关键词： Power system stability Stability criteria Resource management Evolutionary computation Indexes Transient analysis

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Transient and Steady-state Response of AlGaN/GaN Terahertz Detectors under Sinusoidal Excitation of Different Intensities

Transient and Steady-State Response of AlGaN/GaN Terahertz D...

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International Conference on Infrared and Millimeter Waves

作者： Huiting Xia Zhengya Yin Shanshan Jia Lei Cao State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

Terahertz field effect transistors (TeraFETs) based on AlGaN/GaN materials have high responsivity and sensitivity at room temperature. Based on the hydrodynamic equations, the nonlinear voltage response (transient and steady-state) of this type of THz detector was numerically calculated by finite difference method under THz excitation with different frequencies and intensities. Comparisons with the existing analytical formula and the analysis of the influence of viscosity coefficient on the response were also presented.

关键词： Viscosity Temperature sensors Sensitivity Detectors Voltage Mathematical models Wide band gap semiconductors

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Application of an LLCL filter on three-phase three-wire shunt active power filter

Application of an LLCL filter on three-phase three-wire shun...

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International Conference on Telecommunications Energy (INTELEC)

作者： Cong Liu Ke Dai Kewei Duan Xin Wang Yong Kang State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

This paper concentrates on a new high-order output filter, named LLCL filter, and its application issues on the three-phase three-wire shunt active power filter (SAPF). The LLCL topology is constructed by replacing the capacitor of the traditional LCL filter with an LC branch that resonant at the switching frequency. The SAPF with an LLCL filter exhibits excellent switching frequency harmonic attenuation capability, which is beneficial to the harmonic compensation for nonlinear load. System stability problems aroused by resonance are investigated, and a passive damping method by adding a real resistor in the LC branch is adopted for simplicity. The selection of the damping resistor is based on the criteria of minimization of power loss as well as maintaining good harmonic compensation performance. Simulation and experimental results have been presented to verify the theoretical analysis.

关键词： Power harmonic filters Active filters Power filters Damping Harmonic analysis Switching frequency Resistors

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Research on supersonic and subsonic vacuum arc simulation

Research on supersonic and subsonic vacuum arc simulation

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Electrical engineering (CIYCEE), IEEE China International Youth Conference on

作者： Ke Sun Ling Dai Lingfeng Xiang Fuchang Lin State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (数字)9781728196596

ISBN: (纸本)9781728196602

In this paper, according to the magnetohydrodynamic (MHD) model of vacuum arc, vacuum arc is regarded as a two-fluid model of mixing electrons and ions, and the momentum equation, mass equation and energy equation of the fluid are coupled with the magnetic transfer equation and Maxwell equations. After that, the momentum equation and energy equation are secondary developed in Fluent, and the momentum equation and energy equation in Fluent are modified. According to the different characteristics of supersonic arc and subsonic arc, different anode boundary, cathode boundary and side boundary, namely fluid wall boundary conditions are set, and supersonic arc and subsonic arc are solved in fluent. The relationship between arc current and arc pressure, arc density, arc velocity and axial current density in supersonic arc and subsonic arc is obtained.

关键词： Magnetohydrodynamics Fluids Mathematical model Current density Anodes Vacuum arcs Cathodes

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