TARANIS—A Satellite Project Dedicated to the Physics of TLEs and TGFs

TARANIS “Tool for the Analysis of RAdiations from lightNIngs and Sprites” is a CNES satellite project dedicated to the study of impulsive transfers of energy between the Earth atmosphere and the space environment. Such impulsive transfers of energy, identified by the observation at ground and in space (rocket, balloons, FORMOSAT 2 satellite) of Transient Luminous Events (TLEs) and the detection on satellites (CGRO, RHESSI) of Terrestrial Gamma ray Flashes (TGFs), are likely to occur in other astrophysical environments as well. The TARANIS mission and instrumentation is presented. The way the TARANIS programme (associated ground-based and balloon-based measurements included) may answer questions about the physics of TLEs and TGFs is examined. The questions addressed include: TLEs and TGFs source regions, associated phenomena, transfers of energy between the radiation belts and the atmosphere, TLEs and TGFs generation mechanisms, input parameters to the modelling of the variation of the atmosphere and the electric circuit.     

Rotation and Shape of High Altitude Reflectors Controlled from the Ground

Passive, inverted-dish shaped communications mirrors made of a thin wire mesh may be maintained in a stationary position above most of the atmosphere by the pressure of reflected radiation beamed at the mirror from the ground. We show that by beaming at the mirror an appropriate mixture of linearly and circularly polarized radiation, and by inducing small periodic variations of the plane of polarization, one can monitor and sufficiently control wire orientation in the mirror, which allows one to reduce mirror weight and/or set the mirror in rotation. Mirror rotation in turn can modify mirror shape, open up flaps, and allow synchronized messages to be sent to prechosen locations.     

柱状金属微粒-电介质复合材料的等效介电常数

基于介质圆柱电磁散射理论和等效介质理论，导出了金属柱微粒-电介质复合材料的等效相对介电常数的表达式。数值结果表明：入射波频率低于某一频率或金属柱掺料的体积分数增大到一定数值时，复合材料的等效相对介电常数实部会变为负数。     

Acoustic Propagation at Microwave Frequencies

Techniques for the generation, propagation, and detection of sound at microwave frequencies have been investigated. Transmission and reflection experiments with quartz crystals are discussed with the design of a microwave delay line as the final product. Various limitations for the system were discovered, and methods of overcoming them were studied. Experiments with zinc oxide transducers were performed in an attempt to overcome the high insertion losses in quartz crystals. Propagation effects in various crystals geometries were also studied.     

Radio noise level due to electric power lines and its relation to line design parameters

The main results of radio noise measurements taken in Poland for 220 and 400 kV power lines are presented. The influence of various line parameters, such as conductor diameter and number, phase spacing, and height of conductor above ground on the radio noise level for power lines is discussed. The basic philosophy of choosing the line parameters and route at the design stage in Poland is described taking into account radio noise levels, electrical field gradients, and corona losses.     

Stimulated electromagnetic emissions by high-frequency electromagnetic pumping of the ionospheric plasma

A high frequency electromagnetic pump wave transmitted into the ionospheric plasma from the ground can stimulate electromagnetic radiation with frequencies around that of the ionospherically reflected pump wave. The numerous spectral features of these stimulated electromagnetic emissions (SEE) and their temporal evolution on a wide range of time scales are reviewed and related theoretical, numerical, and simulation results are discussed. On long (thermal) time scales the SEE constitutes a self-organization of the ionospheric plasma which depends on the interaction of nonlinear processes in a hierarchy of time scales in response to the electromagnetic pumping. Particularly, the appearance of the rich SEE spectrum is associated with the slow self-structuring of the plasma density into a spectrum of magnetic field-aligned density striations. The dependence of the SEE on electron gyroharmonic effects and the presence of density striations suggests that the existence of a magnetic field in the plasma is important for plasma turbulence to dissipate into non-thermal electromagnetic radiation during the long time quasi-stationary state of the turbulence evolution.     

The menagerie of geospace plasma waves

Sounding rockets and satellites have discovered a large variety of plasma waves within the Earth's magnetosphere—geospace. These waves are found over a frequency range of millihertz to megahertz. The frequency ranges are generally associated with characteristic frequencies such as the plasma frequency and gyrofrequency. Most waves are generated by hot or streaming magnetospheric plasma; some waves are due to lightning discharges, to intentional man-made transmitters or to incidental radiation from power transmission systems. Propagation of waves from the observation region back to a probable source region can be modelled using ray tracing techniques in a model magnetosphere where the electron number density, ion composition and magnetic field vector is specified. Information in addition to the common amplitude-frequency-time spectrograms can be obtained from the received waves using multiple antennas and receivers. Cross-correlation of the wave electric and magnetic components can provide information on the wave polarization and direction of propagation and on the wave distribution function.     

适用于气动学问题的DRP类有限差分方法

研究了一类低耗散低色散的高阶精度有限差分方法,目的是直接计算非定常欧拉方程用于气动声学问题.采用的数值方法是空间四阶、时间三阶精度的色散关系保持(DRP:dispersion-relation-preserving)类有限差分格式,通过波动方程算例验证了格式模拟波动问题的能力;采用加变幅值的高波数人工耗散项来抑制高频数值振荡,使得该格式可推广用于含激波、初始间断或非线性波动的问题.通过含激波、初始间断条件的算例验证了所用变幅值人工耗散的有效性,最后作为初步应用计算了二维亚、超音速均匀流中简单点声源辐射问题,得到了很好的结果,表明此类方法在气动声学问题计算上深有潜力.     

蜂窝结构吸波材料等效电磁参数的计算

用介质波导理论导出了蜂窝结构吸波材料的特征方程;数值计算了蜂窝结构中电磁波传播常数及其等效介电常数与等效磁导率。其主模的传播常数是介于芯与壁单质平面波的传播常数之间,等效电磁参数具有色散特性。     

Type-III radio bursts and their interpretation

The observations of type-III solar radio bursts are briefly reviewed to set requirements on a model for their interpretation. The most important of these requirements is that the source must be an electron stream which is in a state of continuous quasilinear relaxation and which initially must have a nearly monotonically decreasing velocity distribution. The problem of constructing a model is broken into three parts: (1) The plasma wave source which depends on the interaction of the electron stream with electron plasma waves. (2) The radiation source which depends on the interaction of plasma waves and transverse electromagnetic waves or in a magnetized plasma the ordinary and extraordinary modes of magnetoionic theory. (3) The propagation of radiation between the source and the observer which depends on the transmission of radiation through a scattering refracting absorbing magnetized plasma.Progress on a model for the plasma wave source is reviewed and it is concluded that no existing models are adequate. The equations which would lead to an adequate model are written down, but not solved. These include, in addition to collisional damping, Landau damping both by the exciting stream and the background plasma, and spontaneous and induced processes for a three-dimensional distribution of plasma waves. Possible limitations to a quasilinear approach such as pile-up of plasma waves and nonlinear effects are considered. Processes which affect the gross structure of the source such as electron trajectories in coronal streamers and electron scattering by inhomogeneities are reviewed.Progress on the radiation source is considered both in the absence and presence of a magnetic field. At high frequencies (e.g., 80 MHz) observations of radiation near the fundamental and second harmonic of the plasma frequency allow a unique determination of source size and the energy density in plasma waves within the uncertainties of geometry by source ray tracing. This determination is extremely critical because the fundamental must be amplified and thus production of the fundamental is effectively a much more highly nonlinear process than production of the second harmonic. At low frequencies (e.g., 500 kHz) the second harmonic is shown to be dominant because amplification of the fundamental becomes an inefficient process.Calculations of scattering of radiation in a random medium are reviewed. It is concluded that these are adequate at high and low frequencies, but have not been carried out properly at intermediate frequencies where amplification of the fundamental may still be present. It is shown in particular that when scattering is taken into account at high frequencies all observations can be explained by isotropic emission near the second harmonic. At low frequencies the nature of the scatterers is determined by source occultations unlike the case at high frequencies where these are free parameters. This fact allows the possibility of determining true source sizes at low frequencies by subtracting out the contribution due to scattering. A mechanism for producing the possibly observed linear or highly elliptical polarization of type-III bursts, which must be imposed far from the source due to Faraday rotation, is reviewed.Finally, the questions of what remains to be done and what we can hope to obtain upon completion of this work are briefly considered.The National Center for Atmospheric Research is sponsored by the National Science Foundation.     

地线设计在PCB电磁兼容性中的作用

简介了电磁兼容性(EMC)的基本概念,并结合某项目实际应用,说明地线设计的一点改变即可在PCB电磁兼容方面起到重要作用.     

Effects of Particle Beams in the Solar Atmosphere

This work addresses the observational and physical effects of particle beams in the solar atmosphere. Mainly electron beams are considered, but also some effects of proton and neutral beams are mentioned. Briefly describing acceleration mechanisms of superthermal particles, the main attention is devoted to effects influencing the particle beam propagation. The collisional energy losses and pitch-angle scattering, return current effects, mirroring in the converging magnetic field, and the scattering in the Alfvén and whistler wave turbulence in specific situations are considered. The role of quasi-linear relaxation is discussed. Examples of observations showing effects of particle beams in the solar atmosphere are presented throughout the paper. Separate chapters are devoted to processes connected with particle beam bombardment of dense layers of the solar atmosphere: hard X-ray and -ray flare emissions, evaporation process, asymmetry of optical chromospheric lines, and impact linear H line polarization. The beam induced energy release processes are also included. The presented effects of particle beams are summarized in the conclusions and future prospects are suggested.     

Analysis of a Long-Distance System Measuring the Concentration of Atmospheric Gaseous Pollutants

A detailed inaccuracy and sensitivity analysis of a long-distance air pollution detection system, using a laser measuring the resonance absorption of polluting molecules, is introduced. The noise and the dynamic range of the radiation detectors used, the atmospheric inhomogeneities, and the atmospheric propagation losses of the electromagnetic radiation are considered. In addition, the best measuring path length as a function of a molecule density and atmospheric transparency and irregularity is discussed.     

The heating of the solar corona

In this paper a discussion is given of the present state of the theory of the heating of the solar corona by shock waves. Arguments are presented why the main contribution to the mechanical energy flux is of acoustic origin, while estimates for the amount of acoustic energy generated in the convection zone as well as the deviations from isotropy are given. During propagation through the atmosphere acoustic waves develop into shock waves after a distance of a few scale heights in the chromosphere. The heating of the outer layers by dissipation of shock waves is found to be sufficient to account for the observed radiative and corpuscular energy losses.Much emphasis is laid on the competitive role played by the four fundamental processes of energy transfer: mechanical heating, radiation, heat conduction and convection of energy in establishing the equilibrium structure of the corona. The atmosphere may be divided in several regions according to the predominance of one of the energy processes mentioned above.The physical properties of the chromosphere and the solar wind are discussed only where they are intimately connected with the problem of the heating of the corona.The most important aspects of the influence of a magnetic field on the structure and the heating of the corona in magnetically active regions are briefly mentioned. Special attention is paid to the strong channelling of heat flow along the field lines and its consequences for the structure and dynamics of the chromosphere-corona transition layer.     

水下爆轰燃气泡形态与激波传播过程研究*(爆震专刊)

针对脉冲爆轰发动机在水下工作过程中形成的燃气射流问题,搭建了水下爆轰燃气实验系统,研究了第一个爆轰循环在水下的燃气泡发展变化过程。建立了基于气液两相双流体模型的脉冲爆轰发动机水下喷射模型,采用时-空守恒元和求解元方法,模拟了爆轰波退化为激波在水中的传播及衰减过程。研究结果表明：燃气泡前期受外界水环境阻滞作用呈现“豌豆状”形态,充分发展阶段气液交界面逐渐失稳,在达到最大尺寸后开始收缩并在中心轴线位置出现凸出的射流；水下爆轰燃气射流发展过程中同时存在脱离燃气泡的水中前导激波和管口燃气泡内的高压区两部分,水中前导激波在传播过程中压力迅速衰减至常压量级,而管口燃气泡内则一直保持较高压力；中心轴线区域气液交界面处反射激波的回传使管口附近出现回击现象,并导致前导激波波阵面上压力峰值逐渐出现在30°方向上。     

单端正激ZVT功率变换器实现

介绍一种单端正激工作方式的零电压过渡（ＺＶＴ）软开关ＤＣ－ＤＣ变换器;描述该变换器的原理和特征;给出了应用ＺＶＴ软开关技术和集成控制块ＳＧ３５２５Ａ的２４Ｖ／９ＡＤＣ－ＤＣ变换器电路和实验结果。     

基于OpenFOAM的三维H2/Air连续旋转爆轰流场数值模拟

为进一步研究旋转爆轰流场特征,基于开源计算流体动力学软件OpenFOAM,采用9组分19步的基元化学反应模型,对H2/Air连续旋转爆轰流场进行了三维数值模拟,得到了旋转爆轰波稳定传播时燃烧室内部流场的详细结构,研究了燃烧室头部激波的传播特性,分析了旋转爆轰燃烧室的压力增益性能。结果表明:旋转爆轰波后的第一道反射激波在由燃烧室外壁面向内壁面传播过程中反射激波的高度增加并在靠近内壁面附近与滑移线交汇形成局部高温高压区域;旋转爆轰波在外壁面位置处相位约落后于内壁面0.003rad～0.15rad,其相位差随燃烧室曲率差的增加而增大;燃烧室头部反射激波数目受到曲率差和进气总压的影响,燃烧室曲率差增大,反射激波数目减少,进气总压增大,反射激波数目增多;燃烧室压力增益保持在0.3以上,在进气总压一定的条件下,压力增益随着燃烧室曲率差的增大有增加的趋势。研究结果揭示了三维旋转爆轰流场的精细结构和燃烧室头部激波的传播规律。     

ZCS-PWM boost rectifier with high power factor and low conduction losses

A new single-phase high power factor rectifier is proposed, which features regulation by conventional pulsewidth modulation (PWM), soft commutation, and instantaneous average line current control. A new zero-current-switching PWM (ZCS-PWM) auxiliary circuit is configured in the presented ZCS-PWM rectifier to perform ZCS in the switches and zero-voltage-switching (ZVS) in the diodes. Furthermore, soft commutation of the main switch is achieved without additional current stress by the presented ZCS-PWM auxiliary circuit. A significant reduction in the conduction losses is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices are involved in the circulating current path and the proposed rectifier uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. Seven transition states for describing the behavior of the ZCS-PWM rectifier in one switching period are described. The PWM switch model is used to predict the system performance. A prototype rated at 1 kW, operating 60 kHz, with an input ac voltage of 220 V/sub rms/ and an output voltage 400 V/sub dc/ has been implemented in laboratory. An efficiency of 97.2% and power factor near 0.99 has been measured. The analysis and design of the control circuitry are also presented.     

弓网电弧辐射特性及对机场下滑信标的影响

为获得弓网电弧辐射特性及从理论上分析其对机场下滑信标的影响。选择典型电气化动车线路,首先基于CISPR16-1标准,利用电磁干扰接收机对电分相和普通点处的弓网电弧电磁辐射进行点频测试,获得了其在下滑信标台频谱内的辐射特性,然后基于电波传播理论,以电气化轨道平行跑道为例,分析了弓网电弧电磁辐射对飞机导航的影响。结果表明：电弧电磁辐射具有一定的随机特性,普通点处产生的电磁辐射场强小于电分相处;普通点的电磁辐射不会对飞机的导航产生干扰;当轨道距跑道中心的距离分别为700、120和60 m时,电分相拉弧点距下滑信标台天线的距离应分别小于3 291、546和249 m时才不会对飞机的导航产生干扰。本结果能够为轨道电气化和民用航空这两大工业体系在机场区域的电磁兼容性设计提供依据。     

ATS-5 Millimeter Wave Propagation Experiment

This paper describes the design of the millimeter wave experiment aboard the ATS-5 satellite. This equipment is the first millimeter wave communications equipment in space. The function of the equipment is to provide earthspace propagation data at Ku- and Ka- band frequencies. The designs of the phase locked Ka- band receiver, the Ku-band transmitter, the antennas, and the telemetry and processing equipment are described. Mechanical and environmental problems are also discussed.