基于静电探针测量对双潘宁离子源的弧特性研究

本文介绍了采用静电探针的逐点测量法和锯齿波扫描测量法来测量离子源放电中等离子体参数,在此基础上利用静电探针所测量的离子饱和流信号作为控制部分反馈变量,使用闭环控制对22厘米双潘宁离子源的等离子体进行调节,并且利用探针所测量的结果对弧特性进行了初步的分析.     

强流双潘宁离子源弧特性研究

针对22cm双潘宁离子源,研究了其弧流与放电调节参数的关系以及二次进气的效果,确定了拉长弧流脉宽、提高弧流强度与稳定性、达成离子源合适工作状态的措施,为获得高品质的弧流提供了依据。离子源弧特性测试研究结果对提高强流离子源的工作性能以实现NBI系统强流准稳态运行有重要的指导意义。     

火花氢离子源的等离子体特性研究

提出了氢离子源等离子体的一维动态CRAM（collisional radiative atomic and molecular）模型，计算了非平衡态（NTE）下等离子体中分子、电子、离子、基态原子、激发态原子共9种粒子浓度以及电场强度、气体温度和电子温度在一个脉冲内随时间和轴向空间的分布。计算表明：氢离子源中粒子分布在轴向极不均匀，阳极附近有很高的粒子浓度；氢原子离子占总离子数的93．9％，与文献值相符；巴耳末系谱线强度与文献值符合较好。     

电子回旋共振等离子体源的特性

简要描述了一台频率为２．４５ＧＨｚ的电子回旋共振（ＥＣＲ）等离子体源的特性测试,结果表明,放电室内的等离子体密度和电子温度与静态磁场、微波输入功率和真空度等参数均有着密切关系。当磁场达到共振条件８７．５ｍＴ时,等离子体很易产生,但等离子体密度的最大值却出现在９３ｍＴ处。ＥＣＲ源在真空度为０．１—ｌＰａ间均能运行。由石英、Ａｌ２Ｏ３陶瓷和ＢＮ构成的微波输入富有良好的阻抗匹配,在微波功率为２００—７００Ｗ间,反射系数仅为１％,等离子体密度达５．８×１０１１ｃｍ－３,电子温度为３－１２ｅＶ,该源的寿命超过３００ｈ。     

中子管冷阴极潘宁离子源起弧特性测试

实验建立了中子管冷阴极潘宁离子源起弧特性的测试方法。该方法采用对比实验方法对中子管离子源起弧时刻进行研究,可得到离子源起弧规律,发现同步脉冲与中子脉冲之间的差异。通过改变变量,对存在的差异进行研究,得到中子脉冲时序关系,为脉冲中子类测井仪方法研究提供数据基础。     

阴极真空弧源磁过滤弯管偏压模式研究

为了改进阴极真空弧等离子体通过磁过滤弯管的传输效率 ,测定了磁过滤弯管出口离子电流与阴极弧流的关系。结果表明 :磁过滤弯管内表面中 ,靠近大径中心一侧的表面 （内侧面 ）和远离大径中心一侧的表面 （外侧面 ）与等离子体的相互作用是独立的。存在两种向磁过滤弯管内表面运动的离子流 :离子碰撞导致的横向扩散离子流和从阴极弧出来的较高能量的惯性离子流。两种离子流通过磁过滤管的传输过程有不同的机制。整个磁过滤弯管偏压较仅仅Bilek板偏压有更高的离子传输效率 ,Bilek板偏压对磁过滤弯管离子传输起主要作用。     

阳极结构对直流非转移型等离子体射流特性的影响

本文介绍了自行研制的直流非转移弧等离子体炬的结构和工作原理,研究了不同阳极结构等离子体射流的特性与气体流量、弧功率的关系,以及侧向垂直送气对射流形貌的影响。结果表明,阳极结构对等离子体射流特性的影响较大,弧压随着阳极压缩角的增大而下降,较小压缩角的射流稳定性更好;通道直径较小的等离子体射流刚性更强;不同阳极结构的等离子体炬可以有不同的应用领域。     

一种用于煤粉点火等离子体发生器的电弧特性研究

介绍了一种用于煤粉点火等离子体发生器的实验装置,由一对并联的条形平行布置的阳极和同平面布置的圆柱形阴极构成,它们设置在煤粉输运通道中。采用高速CCD摄像和电弧电气参数测量等方法,研究了电弧形状、弧根的运动规律等。试验结果表明:（1）阳极弧根沿电极轴向无规则快速跳动及在两条电极间交替跳跃,这种弧根的快速跳跃有利于降低阳极损耗;（2）电弧在两条阳极之间的弧室内呈现不规则快速变化扭曲形状,使电弧弥漫于整个弧室,煤粉通过电弧放电通道高温区时与电弧混合而点火,使等离子体点火效率有了显著提高。     

核阀零件激光熔覆工艺合理性研究

采用激光熔覆、等离子喷焊和电弧堆焊３种工艺分别对核阀阀瓣密封面进行了Ｃｏ基合金的强化处理,对所形成的熔层的组织和性能进行了试验分析,对３种工艺的综合成本进行了对比。结果表明：激光熔覆工艺具有生产率高、能耗低,熔覆层加工余量小,成品率高以及综合成本低等特点;激光熔覆核阀零件的质量和使用寿命明显高于等离子喷焊和电弧堆焊处理的核阀零件。因此,激光熔覆工艺是一项很有发展前途的新技术。     

电弧等离子体煤粉燃烧器的研究

利用电弧等离子体温度高、单位体积热功率密度高、化学活性高等特点,设计出了结构简单、能稳定燃烧的电弧等离子体煤粉燃烧器;这种燃烧器只需提供一定的等离子体功率,对煤粉进行气化和活化后就能和主进风产生猛烈的燃烧。经初步实验研究,这种燃烧器能稳定地燃烧,主燃烧室出口处火焰中心温度约为1150-1260℃,输入的等离子体功率与所进煤粉燃烧的热功率之比约为1:25。     

Studies on fluid model for numerical simulation of gas discharges in color plasma displays

The fluid models of gas discharge in alternating current plasma display panel (AC PDP) cell are discussed.From the Boltzmann equation, the hydrodynamic equations are derived, but this model consumes much computational time for simulation. The drift-diffusion approximation model and the local field approximation model are obtained to simplify the numerical computation, and the approximation conditions of these two models are discussed in detail. The drift-diffusion approximation model gives more satisfactory result for PDP simulation, and the expression of energy balance equation is given completely in this model.     

Method for super Fresnel resolution in electromagnetic diagnostics of inhomogeneous plasma

The method of electromagnetic diagnostics is suggested, which promises to perform super Fresnel resolution of plasma inhomogeneities, that is resolution, distinguishing details smaller than Fresnel radius. To realize super Fresnel resolution it is suggested to represent the wave field of the source in the form of double weighted Fourier transform (DWFT), deals with Fourier transform simultaneously in coordinates of the sources and in coordinates of receivers. Important property of DWFT is that DWFT transfers into geometrical optics (GO) approximation for smooth inhomogeneous media and becomes equivalent to the Rytov or to small angle Born approximation in the case of weak inhomogeneities. As a result, inverse DWFT allows obtaining linear integral of plasma density both for large scale inhomogeneities, as in GO approximation, and also for inhomogeneities, whose transverse sizes are small as compared with Fresnel radius. DWFT embraces also the results of the phase screen method and allows to take into account phenomenon of micro-multirayness and to describe strong amplitude fluctuations.Using inverse DWFT algorithm, the authors study resolution of systems consisting of discrete sources and receivers. Both analytical estimates and the results of numerical modeling evidence opportunity to observe small scale plasma inhomogeneities with super Fresnel resolution.     

磁驱动旋转电弧运动图像及弧电压脉动的实验研究

磁驱动旋转电弧产生扩散电弧等离子体过程中有许多有趣的物理现象。本文利用高速摄影技术研究了大气压条件下、非均匀磁场中、大尺度磁驱动旋转氩电弧的电弧结构;在一定的弧电流和外磁场条件下,电弧的平面形状表现为不断发展和增长的螺旋结构,电弧螺旋结构的破裂往往产生于阴极附近的等离子体射流。采用图像分析的方法计算了外部磁场作用下阳极斑点沿弧室内壁的移动频率,分析了磁驱动旋转电弧运动过程中的弧电压脉动现象。结合电弧图像分析和电弧电压脉动及其FFT分析得出:电弧电压的大幅波动与多层电弧螺旋结构破裂和重建相关,而电弧电压的小幅波动则是弧根小幅跳动引起电弧拉长和收缩的结果。     

Comparative assessment of application of low melting metals with capillary pore systems in a tokamak

Capillary-pore systems (CPS) with liquid metals are considered as advanced plasma facing material for application in DEMO-type fusion reactor. The estimation of opportunity of liquid Li, Ga and Sn application is carried out on the basis of its physical, chemical and technological properties, and with respect to prospective design of the tokamak in-vessel elements and technology.It has been shown that Li now is the most attractive and most investigated liquid metal for fusion devices application with CPS. The temperature limit for normal operation is about 550 °C and determined by appropriate Li flux to plasma due to evaporation. Wide range of structural materials is appropriate for Li based in-vessel elements.Ga and Sn are very corrosive and embrittlement inducing metals. As a result the temperature limit of these application is determined by compatibility with structural materials of CPS and in-vessel element. Only W can be used with Ga and Sn up to 500 °C. Moreover these metals have lower thermal properties comparing to Li.Surface temperature analysis for possible in-vessel element design (1 mm thick of porous W based CPS) has shown the similar power flux limit ∼21 MW/m² for Li, Ga and Sn application at normal operation. Taking into account the latent heat of vaporization and screening effect with re-radiation the CPS with Li has a priority at ELM and disruption conditions.     

Operational status of the Magnum-PSI linear plasma device

The construction phase of the linear plasma generator Magnum-PSI at the FOM institute DIFFER has been completed and the facility has been officially opened in March 2012. The scientific program to gain more insight in the plasma–wall interactions relevant for ITER and future fusion reactors has started.In Magnum-PSI, targets of a wide range of materials and shapes can be exposed to high particle, high heat flux plasmas (>10²⁴ ions m^?2 s^?1; >10 MW/m²). For magnetization of the plasma, oil-cooled electromagnets are temporarily installed to enable pulsed operation until the device is upgraded with a superconducting magnet. The magnets generate a field of up to 1.9 T close to the plasma source for a duration of 6 s. Longer exposure times are available for lower field settings.Plasma characterizations were done with a variety of gases (H, D, He, Ne and Ar) to determine the machine performance and prepare for subsequent scientific experiments. Thomson scattering and optical emission spectroscopy were used to determine the plasma parameters while infrared thermography and target calorimetry were used to determine the power loads to the surface.This paper reports on the status of Magnum-PSI and its diagnostic systems. In addition, an overview of the plasma parameters that can be achieved in the present state will be given.