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介绍了一种对等离子体边缘进行径向扫描的往复静电探针系统,该系统由高压气源、传输杆、光栅尺、探针组件构成。它在一次放电中能测量主等离子体边缘的温度、密度、悬浮电位、空间电位、离子饱和电流、极向电场、粒子通量等参数的径向分布以及电子温度和密度的衰减长度。测量结果表明,利用该系统测量的主等离子体边缘参数分布与JT-60U、TEXT、HT-7等装置上测量的结果一致。     

层流等离子体射流温度与速度测量

本文分别应用光谱诊断、水冷皮托管及小尺寸杆状热流探针,对自由射入空气中的纯氩层流等离子体射流中心最高温度、滞止压力以及最大热流密度进行了测量,由测量结果导出了层流射流的中心最大速度,得到了射流气体温度和速度的轴向分布及其随工作电流和气流量变化的一些规律,探讨了气体的温度和速度对其向探针表面换热系数的影响。     

探针移动速度对等离子体射流热流密度测量结果的影响

采用自行研制的中心嵌有铜柱感应件的小尺寸杆状热流探针,在低扰动条件下,对射入大气环境的纯氩层流等热离子体射流传向铜探头表面的热流密度进行了动态测量.结果表明,在射流最高温度16500 K、最大轴向速度850 m/s、探针垂直于射流流动方向的移动速度130～260 mm/s的实验参数范围内,随着探针移动速度的提高,测得的热流密度值减小;射流温度和速度越高,探针移动速度对热流密度测量值的影响越大.     

MM-4中电位和分布实验

本文描述了用静电探针测量探针悬浮电位的方法,给出了MM-4电位分布的实验结果。结果表明,轴向电位分布不对称;在等离子体中沿轴向和径向存在双离子位阱。在离子能谱测量中观察到双离子温度。产生这样电位分布的机制,归于会切系统中的斯托沫区和电子枪的不同工作方式。测量的等离子体电位为-200——300V。     

层流高温部分电离气体射流热流密度分布动态测量与分析

采用表面中心位置装有铜探头的平板,对射入大气环境的层流纯氩高温部分电离气体射流冲击平板的热流密度进行了动态测量,分析了测量条件对热流密度及其分布特性测量结果的影响。同时,研制了嵌有铜探头的小尺寸杆状热流探针,在小扰动条件下测量了射流的热流密度分布。结果显示层流等离子体射流具有稳定的能流密度,探针的移动速度对射流中心区域的热流密度测量结果影响很大。     

层流与湍流等离子体冲击射流特性比较

本文采用数值模拟方法,对层流与湍流氩等离子体射流在空气环境中冲击平板时的流动与传热特性进行了对比研究.结果表明,在平板和射流进口间的距离较大时,平板的存在只对其附近的射流参数分布有较大影响,层流等离子体冲击射流的温度与轴向速度的轴向梯度明显小于湍流等离子体冲击射流情形;由于在平板表面形成的径向壁面射流对引射的附加贡献,层流和湍流等离子体冲击射流对环境空气的引射量明显增加.     

非对称磁镜场电子回旋共振氧等离子体刻蚀化学气相沉积金刚石膜

分别应用郎缪尔双探针和离子灵敏探针对非对称磁镜场电子回旋共振氧等离子体的电子参数、空间分布和离子参数进行了测量,分析了气压对等离子体参数及空间分布的影响。利用该等离子体在优化的气压条件下对化学气相沉积金刚石膜进行了刻蚀,并研究了刻蚀机理。结果表明:电子温度为5~10 eV,离子温度为1 eV左右,而等离子体数密度在1010cm-3数量级。随气压的升高,电子和离子温度降低,而电子数密度先增大后减小。在低气压下等离子体数密度空间分布更均匀,优化的刻蚀气压为0.1 Pa。刻蚀过程中,离子的回旋运动特性得到了加强,有利于平行于金刚石膜表面的刻蚀,有效地保护了金刚石膜的晶界和缺陷。     

电子回旋共振离子源等离子体的密度测量

 诊断电子回旋共振离子源等离子体的传统方法是采用传统的单探针无发射时测量伏安曲线,并根据曲线的拐点由理论公式计算出的等离子体密度。本文设计并研制了等离子体密度的测量装置。采用单根朗缪尔探针（该探针可以用来发射电子）测量等离子体的伏安特性。在探针有发射和无发射两种状态下测量得到两条伏安曲线,根据这两条曲线的"分叉点"得到等离子体电位,然后根据该电位直接由计算机计算出电子温度、电子密度。采用该新方法,测量得到的等离子体参量空间电位约为17 V,悬浮电位约为-5 V,电子温度约为4.4 eV,离子密度为1.10×10¹¹cm^-3,与传统方法计算出的等离子体1.12×10¹¹cm^-3相比,两者相差仅1.8％,但新方法效率和精度更高。     

HL-2A装置边缘等离子体的实验观测

HL-2A装置边缘等离子体在中平面的特性是通过可移动的探针组、快速扫描气动4探针和LHW天线边缘的固定4探针进行研究的。用于测量主等离子体边缘的温度、密度、悬浮电位、空间电位、径向和极向电场、雷诺协强、径向和极向等离子体流速及其径向分布。偏滤器靶板上的14组嵌入式静电3探针阵列用于测量同一环向截面的内外中性化板上的电子温度、密度、悬浮电位及其分布。     

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通过中平面活动10探针组、往复快速扫描4探针和低杂波天线口的固定4探针测量了主等离子体边缘的温度、密度、悬浮电位、径向和极向电场、雷诺协强、径向和极向等离子体流速及其径向分布。用偏滤器靶板上的14组嵌入式静电3探针阵列测量了同一环向截面的内外中性化板上的电子温度、密度、悬浮电位及其分布。比较了在孔栏位形和偏滤器位形下边缘等离子体特性的差异,特别是两种位形下边缘温度和密度衰减长度的变化。分析了在多脉冲超声分子束加料和低杂波注入条件下的边界等离子体特性,以及雷诺协强的径向梯度与极向流和径向电场梯度与湍流损失的相互关系。     

利用介质阻挡探针法测量大气压氦等离子体射流电子密度

分别利用电子的漂移速度和等离子体的传播速度计算了大气压下氦等离子体射流的电子密度。     

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The electron densities in the atmospheric pressure helium plasma were calculated by means of electron drift velocity and the jet velocity respectively. The electron velocity and jet velocity can be calculated by means of helium plasma jet current measured by a dielectric probe and plasma discharge current signal measured by voltage probes. The results show that the estimated electron densities of the helium plasma jet calculated from electron drift velocity and the jet velocity are in the order of 10 ¹¹ cm ^-3 and they increase with applied voltage. There is a little fluctuation in the value of the electron density along the jet axis of the plasma. This result is the same as the measured electron density in atmospheric pressure helium non-thermal plasma jet by using a Rogowski coil and a Langmuir probe. This is in one order lower than the electron density measured by microwave antenna.     

Comparative measurements on thermal plasma jet characteristics inatmospheric and low pressure plasma sprayings

The ion and electron temperatures and plasma flow velocities are measured and compared between atmospheric and low pressure plasma spraying systems. The measurements of ion temperature for two systems are carried out by an optical emission spectroscopy which uses the relative emissivities of isolated Ar I emission lines. The electron density and temperature are measured by a Langmuir probe rotating across the plasma jets. The ion saturation currents collected by a Mach probe at two orientations, perpendicular and parallel to the plasma jet, determine the flow velocity. The spatial distributions of electron density, plasma flow velocity, and the associated shock activity in thermal plasma jets are discussed in conjunction with their direct dependency upon the ambient pressures as well as the torch powers. Measurements on temperatures and velocity profiles of thermal plasma jets reveal the general features of the LPPS jet characteristics, i.e., higher velocity flow with lower temperature, longer heating zone of expanded flame, and more extended accelerating zone compared with those of the APS jets. The shock activity clearly exists in the form of standing shock waves in the plasma jet of LPPS in view of flow compression and abrupt velocity drop which are appeared in the results of measurements on the variations of electron density and flow velocity along the plasma jet. In the center of the plasma jet of APS, the electron density is high enough to reach the LTE criterion, and the difference between ion and electron temperatures becomes insignificant as the torch input power increases     

Experimental Study of Planar Langmuir Probe Characteristics in Electron Current-Carrying Magnetized Plasma

Experimental study of planar Langmuir probe characteristics in a magnetized plasma with an electron current along the direction of the magnetic field shows that the usual procedure for determination of the electron temperature and plasma density, which is applicable in a current-free magnetized plasma, gives erroneous results for these plasma parameters. When this procedure is applied on the characteristics measured at two opposite orientations of the probe collecting surface with respect to the direction of the electron drift, different values of the electron temperature are obtained. These virtual electron temperatures and corresponding plasma densities calculated from the measured ion saturation currents are higher and/or smaller than the exact local electron temperature and plasma density. Calculation of particular averages of these quantities is proposed as a possible way to obtain correct results for the local electron temperature and plasma density. These averages are used in the approximate evaluation of the electron drift velocity from the electron saturation currents measured at the two orientations of the probe collecting surface.     

Langmuir Probe Diagnostics of a Low Temperature Non-Isothermal Plasma in a Weak Magnetic Field

This article presents measurements by a cylindrical Langmuir probe in the plasma of a DC cylindrical magnetron discharge át the pressure 1.5 Pa that aim at the experimental assessment of the influence of a weak magnetic field to the estimation of the electron density when using conventional methods of probe data interpretation. The probe data was obtained under the presence of a weak magnetic field in the range 1.10^?2?5.10^?2 T. The influence of the magnetic field on the electron probe current is experimentally assessed for two cylindrical probes with different radii, 50 μm and 21 μm. This assessment is based on comparison of the values of the electron density estimated from the electron current part with the values of the positive ion density estimated from the positive ion current part of the probe characteristic respectively by assuming that at the magnetic field strengths used in the present study the probe positive ion currents are possible to be assumed as uninfluenced by the magnetic field. For interpretation of the probe positive ion current two theories are used and compared to each other: the radial motion model by Allen, Boyd and Reynolds [10] and Chen [11] and the model that accounts for the collisions of positive ions with neutrals in the probe space charge sheath that we call Chen-Talbot model [8]. At lower magnetic field 3 · 10^?2 T the positive ion density values interpreted by using the Chen-Talbot model [8] are in better agreement with the values of electron density compared to those obtained by using the theory [10,11]; therefore the model [8] is used for calculation of the positive ion density from the probe data at higher magnetic fields. The comparison of the positive ion and electron density values calculated from the same probe data at higher magnetic fields shows that up to the magnetic field strength 4 . 10^?2 T with the probe 100 μm and up to 5 . 10^?2 T with the probe 42 μm in diameter respectively the decrease of the magnitude of the electron current at the space potential due to the magnetic field does not exceed the error limits that are usual for Langmuir probe measurements (absolute error ±20%).     

Langmuir单探针诊断电子回旋共振等离子体参数分布特性

本文采用Langmuir单静电探针法,分析诊断了电子回旋共振等离子体的参数分布特性,并分析了微波功率、气压对轴向、径向等离子体空间分布的影响。在微波功率400W~650W范围内等离子体具有较高的密度及良好的径向均匀性。     

Detailed comparison between probe density measurements of glow discharge in argon and in helium

In this article we shall look a bit more closely at some of the fundamental plasma parameters obtained by a cylindrical Langmuir probe within low-pressure electrical gas discharge plasma. The presented measurements were made in argon and in helium glow discharge plasmas. We are mainly concerned with the densities of the charged particles (electrons and ions) within the plasma and the effect of the discharge conditions upon them. The electron density is calculated from the electron current at the space potential and from the integration over the EEDF. The ion density is calculated by using the OML collisionless theory. The parameterization of Laframboise's numerical results is also used for the ion density calculation. In the range of our experimental conditions the results of plasma density, for both gases, tend to show that the ion densities measured with the OML and Laframboise theories exceeds the measured electron densities. The results also show that the plasma electron and ion densities increased with both discharge power and gas pressure.     

层/湍流等离子体射流波动特性实验研究

本文应用电压传感器、光电倍增管及水冷皮托管,对产生射入空气中的纯氩层流和湍流等离子体射流的弧电压波动、发生器出口处的射流光强波动以及沿射流轴线的滞止压力波动进行了测量。结果显示层流等离子体射流各参数的波动幅度远小于湍流射流的对应值;弧电压的波动幅度随气流量的变化明显,但随电流的变化很小;弧电压的波动幅度与其平均值之比随电流增加呈下降的趋势。     

The Effect of Rotating Cylindrical Langmuir Probes in Magnetron Plasmas

Using a cylindrical Langmuir probe, the plasma properties (ion density, electron temperature, floating and plasma potentials) in a magnetron sputter source have been investigated, along one particular line‐of‐sight, but for different probe‐orientations with respect to the B‐field. The plasma in the region hosen for observation is haracterised by electrons, which are magnetised (Larmor radius r_le < both the electron mean‐free‐path λ_e, and plasma extension L) and ions, which are not (their Larmor radius r_I > L, λ_I). Through the development of a simple expression for the electron saturation current at different probe angles relative to the local B‐field, it is possible to correct for the diminished electron currents due to their restricted transport across the field. The results indicate that the measured ion density, electron temperature, floating and plasma potentials are unaffected by the probe orientation, however the electron saturation current is attenuated when the probe is aligned along the B‐field. A simple model for the collection of electrons indicates that classical electron diffusion may not operate in the magnetron, with cross‐field electron transport dominated by anomalous, possibly Bohm, diffusion.