闪电放电通道的等离子体特性（英文）

The plasma characteristics of a lightning discharge channel are reviewed.The spectrum of the natural lightning is investigated by employing the slit-less spectrograph.It is found that the spectrum characteristics are closely related to the intensity of the lightning discharge.The lines in the lightning spectrum are classified into essential lines and characteristic lines,according to the characteristics of lightning spectra with different intensities.The characteristics of the lightning channel and the radiation of the lighting plasma are analyzed in the visible and infrared regions.It is shown that,the visible spectrum of lightning is determined by the radiation generated from the early stage to the development of lightning,while the near-infrared spectrum is determined by the radiation generated after current of lightning reaches the peak.The channel temperature and the electron density are calculated using the information obtained from the lightning spectrum.Both the temperature and the density decrease with the increasing length of lightning channel.Moreover,X-rays and neutrons are produced in the process of lighting mainly due to the pinch effects.     

大气压下重复频率纳秒脉冲气体放电中X射线的辐射特性(英文)

Pulsed discharges can generate high power densities and high equivalent electric fields in plasma to emit X-rays,which is closely related to discharge mechanism.In this paper,discharge characteristics and X-ray emission of typical nanosecond-pulse discharges(corona,diffuse,spark or arc)are reviewed.Especially,the diffuse discharges are observed at pulse repetition frequencies up to 1 kHz.Factors influencing the discharge characteristics and X-ray emission are analyzed,such as the gap spacing,parameters of the applied pulse(amplitude,pulse repetition frequency),anode and cathode materials,and curvature radius of cathode.It is concluded that the maximum X-ray intensity is obtained in a diffuse discharge,and the X-ray intensity is affected by the pulse repetition frequency,applied voltage,anode material,and curvature radius of cathode.For example,X-ray intensity increases with the pulse repetition frequency and the atomic numbers of the anode material,but it decrease with the increase of curvature radius.It is also shown that the cathode material has no obvious influence on the X-ray intensity.     

大气压下柱型微空心阴极放电(英文)

The mechanism of micro-hollow cathode discharge at atmospheric pressure is investigated through simulations using two-dimensional fluid model combined with a transport model for metastable atoms.In the simulations,electric potential,electric field,particle density,and mean electron energy of the discharge are calculated.The results show that the two characteristic regions of the discharge,i.e.cathode drop and negative glow can be distinguished in the simulation.The cathode drop is characterized by strong electric field and high mean electron energy,while quasi-neutral plasma of high density and exists in the negative glow.The peak value of electron density can reach the order of 1017cm-3.The electron temperature varies from several eV to tens of eV.The influence of cathode dimension on the discharge characteristics is also investigated.     

A high efficiency multi-module parallel RF inverter system for plasma induced hydrogen

Hydrogen energy plays an important role in achieving carbon neutralization, and plasma induced hydrogen is an effective production method. One challenge is how to guarantee high efficiency operation with wide power output range of the RF inverter system used to generate the plasma. In this paper, a multi-module parallel topology of a high-frequency inverter is analyzed, in which the power combining network can maintain the soft switching characteristics of the inverter modules. A control method of "ON/OFF + phase shift" is adopted to broaden the output power range of the inverter. The equivalent impedances of different modules are analyzed in detail. A four-module 13.56 MHz high-frequency inverter prototype is built and tested. The results show that the inverter can operate at high efficiency and wide output power range with efficiency improved by at least 5% compared with the traditional parameter design method without considering the effect of paralleled modules.     

XLPE电缆电树枝二次生长特性分析(英文)

In order to study the growth characteristics of electrical trees in XLPE cable under secondary applied voltage, a short cable metal needle defect test device is adopted to study the growth characteristics of the new trees after the electrical trees in XLPE cable under the action of the voltage of 12 kV are influenced by secondary applied voltage (15 kV). The research results show that influenced by secondary applied voltage and voltage increase rate, there will be a peculiar "bush-branch" electrical tree in XLPE cable insulation layer and the new trees under secondary applied voltage have the characteristics of short initiation time, fast growth rate and narrow discharge channel, etc, which shows that secondary applied voltage has a great effect on the secondary initiation and growth of electrical trees in XLPE cable and it is an important factor of accelerating cable aging and breakdown.     

基于不同烧蚀模型的脉冲等离子体推力器壁面-等离子体交互作用的机理(英文)

Ablation excited by current pulses is a very critical physical process in pulse plasma thrusters(PPT).Its effects on wall-plasma interaction directly determine the PPT performances.In order to reveal the process of the ablated wall interaction with the discharge plasma in PPT,ablation models formulated by three different boundary conditions at the wall-plasma interface are studied.These are the two widely used high-speed evaporation models(Model-L and Model-M),and the recently developed Keida-Zaghloul model(Model-K)of the Knudsen layer that takes into account the internal degrees of freedom on the energy flux conservation.First,fundamental mechanisms of the three ablation models are clarified by comparative analysis in order to gain a comprehensive understanding of the wall-plasma interaction.Then,the applicability of different ablation models with the numerical solutions of LES-6 PPT is investigated in detail using magnetohydrodynamic(MHD)modeling.Results show that Model-L and Model-M are actually special cases of Model-K when a simplified jump conditions limited by high velocity at the vapor/plasma interface is used;A ratio of ablation rate in Model-L to that in Model-M is about 0.8at the same wall surface temperature,while it rises to 1 at different surface temperature determined by Model-L and Model-M in PPT.Even though Model-K solution requires significant computational time,it shows more accurate ablation feature for the wall-plasma interaction and possesses better computing precision of impulse bit during post-pulse which is useful for future studies of the late time ablation.     

交直流复合电压下电晕放电实验研究(英文)

Converter transformers are one of the most important electrical apparatuses in the ultra high voltage(UHV) DC transmission systems.The valve side and the low voltage(LV) bushing are stressed by long-term AC and DC composite voltage leading to significant partial discharge(PD) and posing great danger to the insulation system.In this paper AC and DC composite voltage is applied on a metal needle-plate model to produce PD signal sequences,and then the pulse waveshape and frequency spectrum are analyzed and compared with PD signals under conventional AC or DC voltage.In the end,the phase-resolved distribution is analyzed to depict the new characteristics of PD under this composite voltage.     

基于脉冲电压法的10kVXLPE电缆绝缘诊断非线性分析(英文)

The diagnosis of water trees of cable insulation is of great importance as the water-treeing is a primary cause of aging breakdown for the middle voltage cables. In this paper, it is described how the water-tree-aged 10 kV XLPE cables were diagnosed. The cables were subjected to electrical stress of 5.9 kV/mm and a thermal load cycle in a curved water-filled tube for 3, 6 and 12 months of aging in accor- dance with the accelerated water-tree test method. The aged cables were used as the samples for water-tree diagnosis. First, the water-tree degraded cable, was charged by a DC voltage, and then the cable was grounded while a pulse voltage was applied to it for releasing the space charge trapped in the water trees. The amount of the space charge, which corresponds to the deterioration degree of the water trees, was calculated. The effects of DC voltage amplitude, pulse voltage repetition rate and aging conditions on the amount of the space charge were studied. Obtained results show that the amount of the space charge has a positive correlation with the applied DC voltage and the ag- ing time of the cables, and that a peak value of space charge appears with the increase of the pulse voltage repetition rate. An optimum pulse voltage repetition rate under which the space charge can be released rapidly is obtained. Furthermore, the releasing mechanism of space charge by the pulse voltage is discussed. Accumulated results show that the presented method has a high resolution for the diagnosis of water tree degradation degree and is expected to be applied in practice in future.     

直流串联电弧故障的检测方法研究(英文)

It is difficult to detect and extinguish direct current(DC)arc in power electronics systems,and the arc could easily lead to a fire and cause great damage to surrounding equipment.A DC arc generation simulation unit is established,in which DC series arcs are generated by dragging the moving electrode away from the fixed one with the help of the stepper motor.In addition,a ferrite rod antenna is used to receive the electromagnetic radiation signals induced by the arcs.Based on experiments using the unit,the general characteristics of DC arc,including the pulse characteristics of arc current and source output in corresponding time window,and the frequency-domain characteristics of arc current,are studied.With discussion on three detection methods,it is concluded that the variation of current and voltage of arc,the spectrum of the arc current during the discontinuous intervals and the radiating electromagnetic signal are all features that can be adopted for detecting DC series arc.Therefore,a synthetic judgment method is suggested for further study.     

典型地面金属目标在毫米波被动监测中的反射简化模型（英文）

For designing camouflage of ground metal target against millimeter wave(MMW) passive detections,based on the radiation and reflection theories related to MMW passive detection and an assumption of high frequency approximation,simplified models of two kinds of ground metal targets are established.Analysis indicates that the reflection from ground is the leading factor on a ground metal target’s radiant temperature.In an 8-mm imaging experiment,the uneven distribution of radiant temperatures in horizontal and vertical metal plates is directly perceived.In a radiometer experiment,two positions of a radiometer device are utilized to obtain the radiant temperatures of a horizontal metal in two different grounds(made of asphalt and metal net respectively),which are 295.41 K and 301.55 K,respectively.The experimental results are close to the analytical results calculated from the proposed simplified models,which are 306 K and 296 K,respectively.According to the simplified models,different parts of a vertical plate receive incident MMW of different angles from the asphalt background.The radiant temperature of a vertical metal plate obtained from a radiometer experiment at night is 307 K,and it is in coherent with 304.22 K,the result from calculation using the simplified model of vertical plate.Both the analytic results and the experimental results agree with the uneven distribution of radiant temperature.     

大气压下高压亚微秒脉冲激励产生的介质阻挡放电的实验分析(英文)

An experimental device is used to study the characteristics of dielectric barrier discharge(DBD)plasma excited by high voltage sub-microsecond pulse power in atmospheric air.Glass,polytetrafluoroethene(PTFE)and plexiglass are used as dielectric barrier materials.Comparatively homogeneous discharge is obtained within 130 mm diameter area in atmospheric air using the three dielectric materials with gap distances of 4.5 mm,6.5 mm and 6.5 mm,respectively.There is no filamentary discharge observed by naked eyes or by camera with the exposure time of 0.25 s.Gas gap voltage,discharge current,discharge power density,etc.are calculated by using Liu’s equivalent circuit model for pulsed DBD.These parameters are used to study the DBD characteristics.Typically,current varies from tens of amperes to hundreds of amperes in atmospheric air DBD excited by sub-microsecond pulses.The peak power can reach to MW order of magnitude.The average power surface density of 1.0 W/cm2and the average electron density of 1011cm 3can also be obtained in the discharge.Rotational and vibrational temperatures,approximately 400 K and 2 650 K,respectively,are obtained by using the emission spectrum of the discharge.This is the basic work performed for a better understanding of the characteristics of atmospheric air DBD plasma excited by high voltage sub-microsecond pulsed power source.     

裸露金属电极中的亚微秒脉冲常压辉光放电（英文）

In order to better understand the physical mechanism of sub-microsecond pulsed glow discharge with bare metal electrodes,using a one-dimensional self-consistent fluid model,the properties of the discharge at atmospheric pressure are numerically studied.The results show that,a discharge without dielectric layers,i.e.a barrier free discharge,is extinguished only with the decrease of the applied voltage.Only one positive discharge event occurs at the slope of the pulsed voltage.A stable glow of barrier free discharge can be achieved only in short durations of the pulsed voltage.The barrier free discharge always starts with a subnormal glow discharge and then evolves into a normal glow discharge.Moreover,to control the discharge stabilization better,the effects of pulse repetition frequency,pulse duration,rising(front) and falling(slope) times on the discharge characteristics are investigated systematically.It is found that the discharge is comparatively more sensitive to the repetition frequency and the pulse duration,while little affected by the rising and falling times.     

绝缘电极之间雷电冲击下油中放电特性分析(英文)

Looking at the problem of electrical discharge development in mineral oil, it is easy to see that most studies in this area focused on the setups of bare high voltage electrodes having a point-plane electrode arrangement. The setups with insulated electrodes are the mar- gin of these studies but it seems to be important to find the dependences between the paper insulation on high voltage electrode and parameters of the discharges initiated in the vicinity of this electrode. Hence, in this paper the results of researches intended to reveal the role of insulation wrapping on a HV electrode in the mechanism of electrical discharges in transformer oil under lightning impulse of both polar- ities are presented. This role is determined by analysis of the parameters characterizing the discharges (onset voltage, propagation velocity, time to initiation, rise-time of light impulses) and also by observation of their spatio-temporal development and oscillograms of the light emitted by their channels. The research was performed for two model electrode configurations: an electrode with paper insulation and a bare electrode which had the same outer dimensions as the insulated one. The most essential conclusion from performed experiment is related to times to initiation. These times, equal in the case of insulated electrodes and model bare electrode, indicate that the source of "weak points" of the paper-oil insulation system is the oil, not the surface of insulation wrapping or the metal.     

Bright,high-repetition-rate water window soft X-ray source enabled by nonlinear pulse self-compression in an antiresonant hollow-core fibre

Bright,coherent soft X-ray radiation is essential to a variety of applications in fundamental research and life sciences.To date,a high photon flux in this spectral region can only be delivered by synchrotrons,free-electron lasers or high-order harmonic generation sources,which are driven by kHz-class repetition rate lasers with very high peak powers.Here,we establish a novel route toward powerful and easy-to-use SXR sources by presenting a compact experimentin which nonlinear pulse self-compression to the few-cycle regime is combined with phase-matched high-orderharmonic generation in a single,helium-illed antiresonant hollow-core fibre.This enables the first 100 kHz-classrepetition rate,table-top soft X-ray source that delivers an application-relevant flux of 2.8×10^6 photon s^-1 eV^-1 around 300 ev.The fibre integration of temporal pulse self-compression(leading to the formation of the necessarystrong-field waveforms)and pressure-controlled phase matching will allow compact,high-repetition-rate lasertechnology,including commercially available systems,to drive simple and cost-effective,coherent high-flux softX-ray sources.     

高空核电磁脉冲模拟器横电磁波喇叭天线瞬态场简化计算方法（英文）

For conveniently calculating the radiated electric field of transverse electromagnetic(TEM) horn antenna,an approximate simplified analytical calculation method is suggested.This method divides the horn to a system of V-antennas and superimposes the fields of all V-antennas to obtain the field of the TEM horn.The method is compared with the traditional analytical method and numerical method.The obtained results suggest that the proposed method is valid,simple and that it can fastly calculate the radiated electric field of the TEM horn antenna in an arbitrary space with an arbitrary excitation voltage.Based on this method,radiation of the TEM horn antenna of a high-altitude electromagnetic pulse(HEMP) simulator is simulated.Rise time,pulse width,peak value of electric field,and field distribution are analyzed.Results show that the TEM horn antenna can be used in HEMP simulators: the near field waveform is closer to the standard waveform than to the far field waveform; the standards for the rise time and the peak value of electric field are easily satisfied; the pulse width of the radiated field can be increased by broadening the pulse width of an excitation source and by making the antenna of a proper length     

中功率激光器驱动电路的研究与设计

In order to improve the performance of the antenna at low frequency, short circuit branch and coupling feed structure are introduced into the folded broadband single antenna in this paper, then resonant frequency is merged into the antenna using method of stagger tuning, finally, a UWB antenna is designed to work between 800MHz～2700MHz. Analysis are conducted to determine the antenna’s properties. The short-circuit wire location, feeding point location and the length of folded strip are discussed in detail. The SAR is calculated by HFSS simulation software while the antenna is close to a 3D human head model. The research results show that the antenna can cover eight commonly used commercial frequency bands at present, and electromagnetic radiation of the antenna has tiny influence on the human head model.     

Automatic Generation Control Strategy Based on Balance of Daily Electric Energy

An automatic generation control strategy based on balance of daily total electric energy is put forward. It makes the balance between actual total generated energy controlled by automatic generation system and planned total energy on base of area control error, and makes the actual 24-hour active power load curve to approach the planned load curve. The generated energy is corrected by velocity weighting factor so that it conducts dynamic regulation and reaches the speed of response. Homologous strategy is used according to the real-time data in the operation of automatic generation control. Results of simulation are perfect and power energy compensation control with ideal effect can be achieved in the particular duration.     

逃逸电子放电应用的“PROTEUS”高压纳秒脉冲发生器（英文）

Many applications of gas discharge with runaway electrons(DRE) require high-voltage pulse generators(HVPG) with very high increasing rate of output voltage(up to 100 kV/ns),long operation life and low cost.Such HVPGs have to be controlled by external computer for working in combination with other modern equipment.In this paper,some HVPGs development for DRE application in industry and medicine are described.The functional structure and operation principles are discussed for the HVPG of "PROTEUS’ line.It is shown that on different loads,the "PROTEUS" generators can produce high-voltage nanosecond pulse with energy up to 1 J,output voltage amplitude from zero to 150 kV,and pulse repetition frequency from zero to 2 000 Hz.Four models of the "PROTEUS" generators are described.The output voltage leading front duration is 150 ns for the "PROTEUS-I" model,10~20 ns for the "PROTEUS-II",2 ns for the "PROTEUS-III" and 0.5 ns for the "PROTEUS-IV".DRE parameters obtained by using "PROTEUS" HVPGs are demonstrated.Some results of DRE application in solid-state surface modification of natural textile and polymer films are shown as well.     

大气压氦气与氩气等离子体射流形成机理的对比研究(英文)

To compare the formation mechanisms of He and Ar atmospheric pressure plasma jets(APPJs),an intensified charge-coupled device(ICCD)are utilized to observe the dynamic process of APPJ.The experimental results show that,He APPJ is first ignited,which is independent of the dielectric barrier discharge(DBD)between the two wrapped electrodes when the high voltage placed at the downstream.The intensity and APPJ length under positive discharge pulses are bigger than that under negative discharge pulses due to the space charge effect.The He APPJ is formed by the DBD development when the high-voltage electrode placed at the upstream side of tube.However,the plasma plume in Ar APPJ is formed by the propagation of DBD whatever the high-voltage electrode is arranged on upstream or downstream side of ground electrode.The difference in formation mechanism between He and Ar APPJs is mainly caused by the gas properties.Moreover,during the discharges,Ar tends to lead to thermal instability and electron Maxwellian instability.     

A Power Management Scheme for Grid-connected PV Integrated with Hybrid Energy Storage System

The penetration of renewable energy sources(RESs) in the distribution system becomes a challenge for the reliable and safe operation of the existing power system. The sporadic characteristics of sustainable energy sources along with the random load variations greatly affect the power quality and stability of the system. Hence, it requires storage systems with both high energy and high power handling capacity to coexist in microgrids. An efficient energy management structure is designed in this p...