The Stimulated Brillouin Scattering of a Strong Laser in Partially Stripped Plasmas

1.IntroductionThestimulatedBrillouinscattering(SBS)ofalaserinplasmasdescribesaspecialinteractionbe-tweenthelaserandplasmainherentwaves,inwhichthepumpwave(incidentlaserlightwave,withfre-quencywo)isscatteredintoaplasmaelectromag-neticwave(withfrequencyw.)andanionacousticwave(withfrequencyw.).Usually,weassumetheionstobestrippedfully,sotheelectronsandionsinplasmasaretreatedasfree(unbound)chargedparticles.Theeffectsoffreechargedparticlesonthewavepropagationarecalculatedthroughtheelectricchargesep…     

Simulation of nonlinear behavior in an electron cyclotron resonance plasma

1.IntroductionDuringthepastseveralyears,microwaveelectroncyclotronresonance(ECR)plasmasourceshavebeensuccessfullyusedinareasofmicroelectronicfabrica-tionsuchassurfacemodification,etchinganddepo-sitionofthinfilms[l,2].Intheseindustrialapplica-tions,theoperatingstabilityisofparticularconcern.ItiswellknownthatECRplasmasasadieledtricarehighlynonlinear,andthus,arepronetoinstabili-tiesthatcanmakehavocofmanufacturingprocesses.Theusualsolutiontothisproblemistocautiouslychoosesomeregionsofoperatingp…     

A Novel Structure of Slot-Antenna Array for Producing Large-Area Planar Surface-Wave Plasmas

The principle of surface wave plasma discharge in a rectangular cavity is introduced and the distribution of the electromagnetic field within a rectangular waveguide is analysed. A novel structure of a slot antenna array is presented. In comparison with the traditional slotantenna, it is shown that the designed slot antenna array can excite effectively the surface wave coupling into the chamber, and generate a stable large-area high-density plasma. These results are useful for exploring the optimized design of the slot-antenna for surface wave plasmas.     

Interaction of Electromagnetic Waves with Two-Dimensional Metal Covered with Radar Absorbing Material and Plasma

A two-dimensional metal model is established to investigate the stealth mechanisms of radar absorbing material （RAM） and plasma when they cover the model together. Using the finite-difference time-domain （FDTD） method, the interaction of electromagnetic （EM） waves with the model can be studied. In this paper, three covering cases are considered： a. RAM or plasma covering the metal solely; b. RAM and plasma covering the metal, while plasma is placed outside; e. RAM and plasma covering the metal, while RAM is placed outside. The calculated results show that the covering order has a great influence on the absorption of EM waves. Compared to case a, case b has an advantage in the absorption of relatively high-frequency EM waves （HFWs）, whereas case c has an advantage in the absorption of relatively low-frequency EM waves （LFWs）. Through the optimization of the parameters of both plasma and RAM, it is hopeful to obtain a broad absorption band by RAM and plasma covering. Near-field attenuation rate and far-field radar cross section （RCS） are employed to compare the different cases.     

梳状电极沿面放电装置的电场计算

梳状电极沿面放电发生器加峰一峰值12 kV的交流高压实现了沿面放电。应用边界元方法计算了6 kV外加电压下两种梳状电极的沿面介质阻挡发生器的电场,并用它定性地解释了实验结果。     

Propagation of Electromagnetic TM （S-Polarization） Mode in Two-Dimensional Atmospheric Plasma

The finite-difference-time-domain （FDTD） method is applied to simulate the twodimensional propagation of electromagnetic TM （S-polarization） mode in atmospheric plasma and in metal layer for strong electron-neutral collisions. Dependence of the wave attenuation on both plasma parameters and incident wave angle are obtained. It is indicated that for a given electron density profile the attenuation depends strongly on the incident angle, the wave frequency, the width of plasma layer, and the collision frequency between electrons and neutrals.     

Electron Heating of LHCD Plasma in HT-7 Tokamak

Electron heating via lower hybrid current drive （LHCD） has been investigated in HT-7 superconducting tokamak. Experiments show that the central electron temperature Te0, the volume averaged electron temperature 〈 Te 〉 and the peaking factor of the electron temperature QTe = Teo/〈 Te 〉 increase with the lower hybrid wave （LHW） power. Simultaneously the electron heating efficiency and the electron temperature as the function of the central line-averaged electron density （ne） and the plasma current （Ip） have also been investigated. The experimental results are in a good agreement with those of the classical collision theory and the LHW power deposition theory.     

Axial Shock in a Cylindrical Plasma with Current

Hugoniot relations of a two-dimensional axial shock with current and magnetic field in a cylindrical shock tube were investigated by a numerical method. The radial profiles of the magnetic field, electric current, pressures, flow velocities and temperatures between the up- and down-stream radial force-balanced plasma of the shock were revealed by numerical analysis. It is clearly found that the axial shock can lead to two effects： one is an inverse skin effect （i.e., the current density rises towards the center of the conductor）, the another is a reversed current effect which occurs near the edge and about a half radius. It is also found that the radial gradient of pressure, density and temperature all become very large near the center due to the axial shock.     

烟草抗旱生理的研究

在烟草栽培中,土壤干旱是对烟草产量、品质影响较大的自然灾害之一,在我国北方烟区旱害时有发生。近几年对抗旱问题的研究虽受到众多同行的重视,并且在田间灌溉系统上做出了许多成绩,但对烟草本身抗旱能力的研究,特别是烟草抗旱生理方面的研究报道在国内外还不多见。本文对黄淮地区的几个烟草区试品种在土壤干旱条件下,抗旱能力的差异以及有关生理变化规律进行了一些探讨,