利用离子声波朗道阻尼测量氧化物阴极放电中的离子温度

作为等离子体重要参数之一, 特别是在低温等离子体中离子温度的测量一直较为困难. 在磁化线性等离子体装置氧化物阴极脉冲放电条件下, 利用栅网激发离子声波, 通过测量波幅在朗道阻尼作用下随空间的演化, 利用阻尼长度是离子温度和电子温度的函数, 计算得到离子温度为0.3 eV. 测量值与国外类似装置利用光谱诊断所得结果基本相同.     

在HL－1M装置上用弯晶谱仪测量离子温度

本文叙述在ＨＬ－１Ｍ装置上用弯晶谱仪获取Ｆｅ的类Ｈｅ离子谱，用谱线的多谱勒加宽测量等离子体的离子温度，得到的等离子体ＨＬ－１Ｍ装置离子温度为５００—８００ｅＶ。     

聚变等离子体中的快离子压强

本文运用Fokker-Planck方程的慢化近似,考虑存在多种离子成份(包括杂质),假定它们具有共同的温度,我们得到了聚变产生的快离子压强的简单封闭形式表示式。表明在典型的工作温度下(～60keV),D-~3He等离子体中聚变产生的快离子压强约为本底热压强的20％,这与D-T等离子体工作在20keV时的比值几乎相同。因此,D-~3He和D-T在它们相应的预期工作温度下,它们各自的快离子压强对总压强的影响是类似的,然而在更高的温度下,这个比值将变得更大。     

离子温度梯度不稳定性的解析理论

本文用解析方法分别研究了在平板和环形模型中离子温度梯度不稳定性的阈值和等离子体温度参数的关系,发现当离子温度远大于电子温度时,阈值会有明显的升高;而且在两种几何模型中阈值随离子温度变化的趋势是相同的,这一结论与PLT的实验结果是符合的,解析结果与数值计算结果也符合得很好。 关键词：     

HL-1装置离子温度的电荷交换法测定

本文叙述了用自己研制的六道中性粒子分析器(即中性粒子谱仪),测量HL-1托卡马克装置离子温度的实验,给出了在1986年进行的一组放电实验所得等离子体的离子温度及其随放电时间变化的结果,测得的中心离子温度的典型值为474eV,在相应等离子体参数下,Artsimovich经验公式给出450eV     

圆筒电极对离子磁电加热的影响

高效的磁电加热不仅能够提高电子回旋共振(ECR)等离子体的离子温度,还能改善离子的径向和轴向分布,促进ECR等离子体在化学气相沉积金刚石膜刻蚀中的应用.将磁电加热系统中的圆环电极改进为圆筒电极,研究了圆筒电极对离子磁电加热的影响,对比了圆筒和圆环电极加热离子的区别.结果表明:在同一阳极偏压下,圆筒比圆环电极更有利于提高离子温度,圆筒电极加热时各径向位置的离子温度升高的幅度较大,其中圆筒电极内部的离子温度径向分布差异较大,而圆筒下游的离子温度径向分布比较均匀;磁电加热对离子密度的影响很小;采用圆筒电极加热时,有利于离子向轴向下游的输运,改善了离子的轴向均匀性.     

离子回旋共振加热的离子加热

本文在直住几何位形下用线性化动力论得到了离子能量吸收及吸收特征长度的解析表示式，离子能量吸收的主要物理机制是回旋阻尼，波与离子的共振吸收条件是ω－ｌωｃｉ＝ｋⅡνⅡ，其中ω和ωｃｉ分别是波的频率和离子回旋频率，ｋⅡ和ｖⅡ是平行于主磁场方向的波矢和离子速度的分量，ｌ为整数。在等离子体参量慢变化的假定下，也得到了能量吸收半宽度的表示式。结合托卡马克的各种具体情况分别讨论了各种离子回旋共振加热模式的...     

电磁监测试验卫星离子漂移计探测技术

依据电磁监测试验卫星的任务要求,自主研发了等离子体分析仪,用于探测电离层等离子体的离子密度、温度、成分、漂移速度和密度的涨落.等离子体分析仪由阻滞势分析器、离子漂移计和离子捕获计组成,其中离子漂移计用于探测离子垂直轨道方向的漂移速度.通过分析电离层等离子体的离子漂移速度特性,确定仪器的性能指标.离子漂移计传感器采用多层栅网压紧结构,栅网材料选用铍铜,各层栅网之间采用聚酰亚胺绝缘.依据技术指标,详细设计了离子漂移计传感器的窗口尺寸、传感器几何高度和收集极半径.在电子学电路设计时通过前放电路三个可调量程的设计,保证了电路测量范围和精度,并通过实验进行验证.在此基础上,借助意大利国家天体物理研究院行星际物理研究所的地面等离子体环境,完成了离子漂移计的等离子体环境测试.测试结果表明,离子漂移计垂直轨道方向漂移速度测量结果的变化趋势与转台设定值变化趋势一致,且测试精度指标满足设计要求,能够满足电磁监测试验卫星的任务需求.     

杂质离子对等离子体边界参量的影响

采用一维流体模型研究了含有杂质离子的等离子体与器壁材料相互作用给边界等离子体参量带来的影响.通过数值模拟,研究了分别选用碳和钨作为器壁材料时,器壁温度不同情形下热发射产生的电子对等离子体器壁电势、电场强度、热发射电子流以及沉积器壁离子动能流的影响.研究结果发现,当面向等离子体材料表面温度升高时,器壁电势和热发射产生的电流将增加,器壁电场强度和离子沉积器壁动能流则会减小,并且钨作为器壁材料要比碳作为器壁材料对于等离子体边界参量影响更明显.此外,研究了钨作为器壁材料时,碳杂质离子（浓度和电荷数）对等离子体器壁参量的影响.     

激光对宽能域碳离子在双组份等离子体中阻止本领的影响

在线性化伏拉索夫-泊松模型基础上研究了激光辐照下碳离子在双组份等离子体中的阻止本领,重点讨论了不同激光振幅、激光频率、激光角度、等离子体密度和等离子体电子温度对阻止本领的影响。研究结果表明,在全域范围内,激光对阻止本领的影响都非常明显。在低能区域（入射速度为等离子体电子热速度的0～0.1倍）,碳离子的阻止本领主要来自于等离子体中离子的贡献,特别是在入射速度约为等离子体离子热速度时,阻止本领出现了第一个峰值;在中高能区域（入射速度大于0.1倍的等离子体电子热速度）,碳离子的能量损失主要来自于等离子体中电子的贡献,特别是在入射速度约为等离子体电子热速度的1.5倍时,阻止本领出现了第二个峰值。碳离子在等离子体中阻止本领的这种双峰结构体现了不同能量区域等离子体中离子和电子对阻止本领的贡献。另一方面,激光强度或激光频率的增加削弱了阻止本领,阻止本领会随着等离子体密度的增加或电子温度的降低而增强,特别是由于离子引起的低能峰与电子引起的高能峰相比阻止本领的增强更明显。     

重离子束在等离子体靶中的能量损失

借助于线性Vlasov方程,我们研究了重离子束在等离子体靶中的有效电荷数和电子阻止本领。在高速情况下,分别得到了它们的解析表示式。以~(40)Ga,~(74)Ge,~(84)Kr,~(110)pd,~(208)pb及~(238)U等重离子束在氢等离子体中的能量损失为例,将我们的理论结果与Hoffmann等人的实验结果进行了比较。     

Electrostatic cnoidal waves and soliton structures in multi‐ions plasmas

Using a reductive perturbation technique (RPT), the Korteweg‐de Vries (KdV) equation for nonlinear electrostatic waves in multi‐ion plasmas is derived with appropriate boundary conditions. Furthermore, compressive and rarefactive cnoidal wave and soliton solutions are discussed. In our model, the multi‐ion plasma consists of light dynamic warm ions, heavy cold ions, and inertialess electrons, which follows the Maxwell‐Boltzmann distribution. It is observed that in such an unmagnetized multi‐ion plasma, two characteristic electrostatic waves i.e., slow ion‐acoustic (SIA) waves and fast ion‐acoustic (FIA) waves, can propagate. The results are discussed by considering two types of multi‐ion plasmas i.e., H⁺–O⁺–e plasma and H^?–O⁺–e plasma that exist in space plasmas. It is found that for H⁺–O⁺–e plasma, the SIA cnoidal wave and soliton form both positive (compressive) and negative (rarefactive) potential pulses, which depend on the temperature and density of the light and warm ions. However, only electrostatic positive potential structures are obtained for FIA cnoidal wave and soliton in H⁺–O⁺–e plasma. In the case of H^?–O⁺–e plasma, the SIA cnoidal wave and soliton form only compressive structures, while the FIA cnoidal wave and soliton compose rarefactive structures. The effects of light ions' density and temperature on nonlinear potential structures are investigated in detail. The parametric results are also demonstrated, which are applicable to space and laboratory multi‐ion plasma situations.     

On the far IR transmission spectra of high-Tc superconductors

After several years, the Far IR (FIR) results from several laboratories seem to converge. The very FIR transmission data at different temperatures in the normal phase, combined with dc resistivity measurements, lead to a constant plasma frequency in that phase, and a linear variation of collision frequency v_c versus temperature T. Approximately the same plasma frequency can be used to explain the FIR transmission spectra at 7 K from 20 to 200 cm^–1. These remarks obtained from purely FIR data are in good accordance with the recent conclusions of Fiory et al obtained by a quite different method, i.e. electrostatic measurements.     

Nonlinear propagation of fast and slow magnetosonic waves in collisional plasmas

Low-frequency fast and slow magnetosonic waves propagating in electron ion plasmas with damping effects through ions and neutral atoms collisions are investigated. Linear wave analysis is performed to obtain dispersion relation. The reductive perturbation method is applied and it is shown that fast and slow modes of nonlinear magnetosonic wave are governed by damped Korteweg-de Vries (DKdV) equation in the presence of ion neutral collisions in plasmas. The analytical solution of DKdV soliton is presented under the assumption of weak collisional effects and numerical solutions of DKdV equation are also obtained using two-level finite difference scheme with the help of Runge–Kutta method at different plasma parameters. The damping of nonlinear fast and slow magnetosonic wave structures at different times are discussed in the context of space plasma situations where ions and neutral atoms collisions exist.     

Wave Instabilities of a Collisionless Plasma in Fluid Approximation

Wave properties and instabilities in a magnetized, anisotropic, collisionless, rarefied hot plasma in fluid approx‐imation are studied, using the 16‐moments set of the transport equations obtained from the Vlasov equations. These equations differ from the CGL‐MHD fluid model (single fluid equations by Chew, Goldberger, and Low [5,9]) by including two anisotropic heat flux evolution equations, where the fluxes invalidate the double polytropic CGL laws. We derived the general dispersion relation for linear compressible wave modes. Besides the classic incompressible fire hose modes there appear four types of compressible wave modes: two fast and slow mirror modes – strongly modified compared to the CGL model – and two thermal modes. In the presence of initial heat fluxes along the magnetic field the wave properties become different for the waves running forward and backward with respect to the magnetic field. The well known discrepancies between the results of the CGL‐MHD fluid model and the kinetic theory are now removed: i) The mirror slow mode instability criterion is now the same as that in the kinetic theory. ii) Similarly, in kinetic studies there appear two kinds of fire hose instabilities ‐ incompressible and compressible ones. These two instabilities can arise for the same plasma parameters, and the instability of the new compressible oblique fire hose modes can become dominant. The compressible fire hose instability is the result of the resonance coupling of three retrograde modes ‐ two thermal modes and a fast mirror mode. The results can be applied to the theory of solar and stellar coronal and wind models (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Impurity Driven Linear and Nonlinear MHD Cylindrical Waves in a Three Species Plasma

The propagation of axisymmetric linear and nonlinear dispersive waves in a three species plasma to include the thermoelectrostatic effects together with the dissipative effects of main ions has been discussed. The impurity driven MHD fluid modes have been examined when the electrostatic drift has been taken into account. We have discussed the linear propagation of dispersive cylindrical waves in the plasma system for different ion thermal phase number. The thermal force resulting from the collisions between main ion and impurity ion densities (i.e. α_iI = 0) has been neglected. The shock waves and the soliton solutions are obtained for two different cases of the non-collisional plasma and the non-dissipative plasma.     

Distribution functions of positive ions and electrons in a plasmanear a surface

In this study, the velocity distribution functions of the ions and electrons in a collisional presheath and collisionless sheath of a plasma near a wall emitting and reflecting ions and electrons are systematically determined. The collisions in the presheath are modeled by a relaxation time approximation (namely, Bhatnagar-Gross-Krook model, or simply BGK model). To find the variation in electrostatic potential with position, the model and analysis from Emmert et al. (1980), are used. Distribution functions of the ions and electrons in a collisionless presheath and sheath on a wall partially reflecting ions and electrons, therefore, can be exactly obtained. The reflections of the ions and electrons by a wall play important roles in studying heat transfer from a plasma sheath to a workpiece surface, and sputter etching and deposition, ion implantation, and ion scattering spectroscopy. Irrespective of ion and electron reflectivities, velocities of the ions in the presheath and sheath are of highly non-Maxwell-Boltzmann distributions. The electrons in the presheath are close to Maxwell-Boltzmann distributions, whereas those in the sheath are non-Maxwell-Boltzmann distributions. Even though the wall partially reflects ions and electrons, the Bohm's criterion is marginally satisfied at the sheath edge. The computed distribution functions for a completely absorbing surface agree with theoretical results provided in the literature. Good comparison of the resulted transport variables with available analytical work is presented in the companion paper     

Obliquely propagating quantum solitary waves in quantum‐magnetized plasma with ultra‐relativistic degenerate electrons and positrons

The oblique propagation of the quantum electrostatic solitary waves in magnetized relativistic quantum plasma is investigated using the quantum hydrodynamic equations. The plasma consists of dynamic relativistic degenerate electrons and positrons and a weakly relativistic ion beam. The Zakharov‐Kuznetsov equation is derived using the standard reductive perturbation technique that admits an obliquely propagating soliton solution. It is found that two types of quantum acoustic modes, that is, a slow acoustic mode and fast acoustic mode, could be propagated in our plasma model. The parameter that determines the nature of soliton, that is, compressive or rarefactive soliton, for slow mode is investigated. Our numerical results show that for the slow mode, the determining parameter is ion beam velocity in the case of relativistic degenerate electrons. We also have examined the effects of plasma parameters (like the beam velocity, the density ratio of positron to electron, the relativistic factor, and the propagation angle) on the characteristics of solitary waves.     

Generalized model for the nonlinear dynamics of plasma waves driven unstable by energetic ions near the stability threshold

In this paper, an attempt to develop the original single mode theory describing the nonlinear dynamics of a linearly unstable plasma wave, excited by the resonant interaction with energetic ions near the stability threshold to the case of n interacting plasma modes has been made. The effects of an energetic ion source and classical collisional processes represented by the Krook, diffusion and dynamical friction (drag) collision operators are included in the model. For numerical purposes, the problem has been reduced to ten nonlinearly coupled integro-differential equations. In comparison to the previous papers, the system revealed similar (the steady-state, oscillation, and blow-up solutions), as well as quite new types of the amplitudes behaviour, i.e. different levels of competition between the modes.     

Peculiarities of interaction of the cathode stream with anodevapors in a vacuum arc

A one-dimensional model of the quasi-stationary vacuum arc plasma zone is considered in terms of a three-liquid hydrodynamics approximation. It is supposed that atoms evaporated from the anode are ionized in a narrow near-anode zone, slow ions are rapidly maxwellized in the result of Coulomb collisions, ion braking length of the cathode stream may be comparable with a gap size, i.e., the cathode stream breaking is important. Outside the narrow near-electrode zones slow anode and rapid cathode ion flows are maintained, the electron thermal conductivity equalizes the electron temperature