CSR实验环电子冷却装置的纵向电子束温度

电子冷却装置中, 电子束纵向温度是计算冷却力的主要参量之一. 当电子与被冷却离子的相对速度很小时, 纵向冷却力与离子速度呈线性关系, 并且线性区域的宽度与电子束纵向温度有关. 通过分析影响电子束纵向温度的主要因素, 得到了兰州重离子冷却储存环实验环(CSRe)电子冷却装置中电子束纵向温度的大小.     

Mirror Instability with Electron Temperature Effects

Linear kinetic mirror instabilities of a homogeneous magnetized plasma in which both ions and electrons have the bi-Maxwellian distributions are investigated in the lowfrequency and long-wavelength limit. It is shown that, in contrast to the case of cold electrons, the criterion for the mirror instability has an upper limit, above which the mirror mode becomes oscillating one. This can possibly account for the oscillatory variations of observed mirror waves in the space plasma. In addition it is also shown that the growth rate of the nonpropagation mirror mode increases rapidly with the anisotropy parameter and is slightly higher than its value under the cold electron assumption, but that the oscillating mirror mode remains nearly a constant growth rate.     

Ion Beam Probe Measurements of Electron Temperature

The technique for measuring electron temperature with an ion beam probe has been refined, the time resolution reduced and the limitations evaluated. The technique involves sequentially probing the same volume of plasma with beams of different ion species and using the observed secondary ion currents and the known ionizing cross sections to evaluate the electron temperature. Spatial resolution is less than 0.1 cm3 and the time required to obtain a radial temperature profile is presently 10 msec. Detailed measurements have been made on a hollow cathode discharge and the results compared with Langmuir probe and spectroscopic data. Quantitative results can only be obtained with K+ -Na+ beams due to the lack of cross sections for other ion species. Better experimental data has been obtained with Rb+ and Cs+ beams but they cannot be reduced to Tee Theoretical cross sections provide qualitative indications of the system behavior but are not sufficiently accurate to permit quantitative data reduction.     

等离子体电子温度的发射光谱法诊断

电子温度是表征等离子体性质的一个重要参数。由于等离子体放电过程非常复杂,要实时准确测定其电子温度值非常困难。发射光谱法作为一种等离子体诊断技术,因其所使用的仪器相对简单,并采用非接触测量,灵敏度高,响应速度快,可广泛地应用于各种等离子体性质的研究和参数的诊断。文章介绍了测定等离子体电子温度的双谱线法、多谱线斜率法、等电子谱线法、Saha-Boltzmann法、谱线绝对强度法等多种发射光谱法,同时综述了这些方法在等离子体电子温度诊断中的应用,旨在为实际过程中选择合适的等离子体诊断方法提供参考。     

低能带电粒子核反应中电子屏蔽效应的温度相关性

为了揭示低能带电粒子核反应中电子屏蔽效应与温度之间的关系, 在德国鲁尔大学实验室的100kV加速器上系统测量了T=200\textcelsius时元素周期表中第三、四族以及镧系元素氘化靶中d(d,p)t反应的电子屏蔽效应. 由于氘在介质中的溶度(介质对氘的吸附能力)随温度升高而迅速下降, 该温度下金属表面不能形成氘化物, 导致金属性增强, 因而观测到了比常温下更显著的电子屏蔽效应. 这一测量结果可以用德拜模型来解释. 为了进一步验证德拜模型, 还测量了不同温度下氘化Co和Pt靶中d(d,p)t反应的电子屏蔽效应, 得到了电子屏蔽效应和温度 相关性的曲线. 实验结果与德拜模型的预言相符.     

Ar辅助确定Al等离子体电子温度

用Ar气作保护气时 ,Nd :YAG脉冲激光烧蚀Al靶 ,将诱发Ar气电离 ,并产生丰富的Ar离子谱线辐射。文章根据Ar离子谱线辐射信息 ,分析了ArⅡ 385 0 5 7,ArⅡ 386 85 3,ArⅡ 4 0 4 2 91 ,ArⅡ 4 0 7 2 0 1nm等 4条谱线的时间分辨行为 ,计算了Al等离子体的电子温度。结果发现 :Al等离子体的电子温度约 1 5 0 0 0～2 2 0 0 0K ,随延迟时间的增加 ,电子温度单调衰减     

Electron Temperature Relaxation in Afterglow Plasmas: Diffusion Cooling

We have carried out a thorough theoretical analysis of the cooling and heating processes of the electron gas in Ne, Ar and Kr afterglow plasmas. Thus the rate of relaxation of the electron temperature, T_e, is seen to be in good agreement with the experimental measurements when spatial gradients of T_e in the early afterglow and heating of the electron gas by superelastic collisions between the electrons and metastable atoms are accounted for. At low pressures of the rare gases, p_g, the phenomenon of diffusion cooling occurs in which T_e relaxes to an equilibrium temperature, T_ee, which is less than the gas temperature, T_g. This reduction in T_ee below T_g is mirrored in a reduction in the ambipolar diffusion coefficient, D_a, for the rare gas atomic ions and electrons. Thus the D_a can be calculated as a function of p_g using the values of T_ee, and when this is done, properly accounting for the heating by metastable atoms, the calculated and experimental values of D_a in all three rare gas afterglows are seen to be in agreement.     

激光诱导Ti等离子体电子温度的实验研究

室温,常压下,利用Nd∶YAG脉冲激光器产生的波长为1 064 nm, 脉宽12 ns,能量分别180, 230和280 mJ的脉冲激光冲击Ti靶,使用中阶梯光栅光谱仪检测了三种激光能量下对应的光谱。调节延时器DG645的延迟时间,检测了延迟0～500 ns时间范围内Ti等离子体对应激光能量下的发射光谱,分析光谱,可以得到了九条不同的的TiⅠ 和TiⅡ等离子体谱线,证明在该实验条件下,Ti靶能够充分吸收能量电离且离子谱线具有不同的演化速率,利用Saha-Boltzmann法计算并分析Ti等离子体电子温度,实验结果表明：相同的延迟时间,激光能量越大,谱线相对强度越大,电子温度越高,谱线相对强度的变化量随激光能量的变化量增大而增大;在延时0～150 ns内,三种激光能量下的等离子体电子温度和谱线的相对强度都随延迟时间的增加而快速下降,其中280 mJ激光能量下的等离子体电子温度和谱线强度下降速率较快;在150～250 ns范围内,电子温度和谱线强度均随延迟时间的增加有一个缓慢的上升,180 mJ激光能量下的等离子体电子温度和谱线强度的上升速率较快。250～500 ns范围内,三种激光能量下的电子温度和谱线强度均随延迟时间的增加而缓慢下降。     

激光诱导Mg等离子体电子温度的实验研究

利用波长为1 064 nm,最大能量为500 mJ的Nd∶YAG脉冲激光器在室温,一个标准大气压下对Mg合金冲击,改变激光能量,得到相应的Mg等离子体特征谱线。分析谱线,发现谱线有不同的演化速率,同时得到了MgⅠ,MgⅡ离子谱线,证明此实验条件下,激光能量足够Mg合金靶材充分电离。选择了相对强度较大的MgⅠ 383.2 nm, MgⅠ 470.3 nm, MgⅠ 518.4 nm三条激发谱线,利用这些发射谱线的相对强度计算了等离子体的电子温度,激光能量为500 mJ时,等离子体温度为1.63×104 K。实验结果表明：在本实验条件下,Mg原子可以得到充分激发;在200～500 mJ激光能量范围内,等离子体温度随着激光能量的降低而衰减,在350～500 mJ激光能量范围内的等离子体温度随激光能量的变化速度十分明显,200～350 mJ时等离子体温度变化速度迅速减缓;激光能量为300 mJ时,谱线相对强度明显减弱,低于350和250 mJ的谱线相对强度,不符合谱线相对强度会随着激光能量提高而上升的变化趋势,证明发生了等离子体屏蔽现象,高功率激光产生的等离子体隔断了激光与材料之间的耦合。此时的等离子体温度明显升高,不符合变化趋势,这是由于在发生等离子体屏蔽现象时,激光能量被等离子体吸收,导致等离子体温度上升。     

Temperature Effects on Electron Correlations in Two Coupled Quantum Dots

The path-integral Monte Carlo simulation method is used to examine one and two electrons in a system of two coupled disc-like quantum dots (QD) in a zero magnetic field. With this approach we are able to evaluate the one-electron distributions and two-electron correlation functions, and finite temperature effects on both. Increase of temperature broadens the distributions as expected, the effect being smaller for correlated electrons than for single ones. The simulated one- and two-particle distributions of a single and two coupled quantum dots are also compared to those from other theoretical methods. For the one-particle distributions we find a good agreement with those from the DFT approach. The effect of the third dimension or the thickness of the almost two-dimensional disc-like QDs is small for the one-particle distributions, but it is clearly seen in the electron-electron correlation or the two-particle distribution function at low temperatures. The mutual Coulomb energy of the two electrons is found to be temperature-independent, and also, independent of the correlation effects on the dynamics. Computational capacity is found to become the limiting factor in simulations with increasing accuracy or increasing number of particles, and in case of fermions in particular. This and other aspects of PIMC and its capability for this type of calculations are also discussed.     

Pumped Spin-Current in Single Quantum Dot with Spin-Dependent Electron Temperature

Spin-dependent electron temperature effect on the spin pump in a single quantum dot connected to Normal and/or Ferromagnetic leads are investigated with the help of master equation method. Results show that spin heat accumulation breaks the tunneling rates balance at the thermal equilibrium state thus the charge current and the spin current are affected to some extent. Pure spin current can be obtained by adjusting pumping intensity or chemical potential of the lead. Spin heat accumulation of certain material can be detected by measuring the charge current strength in symmetric leads architectures. In practical devices, spin-dependent electron temperature effect is quite significant and our results should be useful in quantum information processing and spin Caloritronics.     

常压高频等离子体电子温度的光谱法诊断

常压高频等离子体由于其无电极污染、能量密度大、温度高及气氛可控的特点而得到了广泛应用,电子温度是影响其使用性能的关键参数,根据发射光谱使用玻尔兹曼图解法计算是最常用且最可行的诊断方法,但由于跃迁几率数据可靠性、环境背景、仪器误差、数据处理误差等原因,不同研究者根据不同谱线计算的结果通常不具有可比性。为了得到可靠性高的电子温度计算结果,针对存在SiO₂颗粒的常压高频空气等离子体,以光谱范围为200～1 077 nm的7通道高分辨光纤光谱仪为测量工具,该研究讨论了元素、光谱段选择对计算结果可靠性的影响。结果表明,由于N₂占电离气体的主要部分且不参与化学反应,N Ⅰ发射谱线是最佳选择,使用738～940 nm内N Ⅰ的谱线计算的拟合度为0.95,计算的电子温度最为可靠;由于Si和O极易结合成SiO₂颗粒,此二元素的能量不再满足玻尔兹曼分布,计算结果的可靠性较差,因此不能使用Si和O元素的发射谱线计算电子温度;使用掺入Ar的谱线同样不能得到可靠的电子温度计算结果。因此,为了有效诊断等离子体电子温度,在不同应用场合中,应当根据实际情况,合理选择测量光谱范围及光谱仪,选取合适的粒子及其发射谱线。     

螺线管磁场缺陷对电子束横向温度的影响

分析了直螺线管磁场缺陷的来源,考虑了电子束的空间电荷作用,采用数值方法模拟计算了磁场缺陷对电子束横向温度的影响 ,获得了电子冷却装置中直螺线管磁场的均匀性要求.结果表明,当相对磁场缺陷小于1× 1 0-3时 ,影响可以被忽略.In order to obtain the tolerance requirement for the magnetic field homogeneity of the solenoids in electron cooling device, the source of the magnetic imperfection and its influence on the transverse temperature of electron beam were investigated by means of numerical simulation, and taking the space charge effect of electron beam into account. The calculated result shows that the influence of the imperfection of magnetic field will be negligible when the relative magnetic field...     

Development of Electron Temperature Measuring System by Silicon Drift Detector

The soft X-ray spectroscopy, laser Thomson scattering and electron cyclotron emission （ ECE ） are usually adopted for electron temperature measurement in fusion research of magnetic confinement. The particular soft X-ray spectroscopy has the very good spatial-temporal resolution and smaller measuring error than laser Thomson scattering, a close spatial-temporal resolution to ECE, absolute measurement ability, and smaller influence by suprathermal and runaway electrons than ECE.     

Fast Electron Spatial Temperature Distribution Studied by X-Ray 2D Imaging

We present the experimental and numerical results of two-dimensional x-ray imaging due to fast electron transport in a solid target. A 40-μm-thick copper film target is irradiated by a lOOm J, 50rs normal incident laser pulse. The full width at half maximum of the x-ray photon dose is 25 μm, and the divergence angle of fast electrons is 25°-30°, which is detected by the pin-hole x-ray imaging technique. The target surface plasma layer is compressed by a ponderomotive force into a depth of 0.2λ. The plasma wave accompanied by fast electrons transporting into the target is studied by dividing the plasma into layers in a radial direction. A narrow fast electron channel, which is approximately 8 μm-10 μm in width, mainly contributes to the x-ray dose.     

弓网电弧温度及导电特性的光谱分析

高铁提速受多方面因素制约，其中弓网离线对受流质量影响很大。在滑动接触模式下，受电弓与接触网的磨损均很严重。弓网离线产生的电弧是造成接触网和受电弓磨损的主要原因之一。电弧温度高，还具有电离特性，因此一般的传感器无法置于电弧中测量。光谱分析法在研究弓网电弧的温度及电子密度方面具有明显优势，基于此可进一步寻找耐磨损的新材料或者灭弧方法。因接触网使用铜合金材料，故选取铜元素特定光谱作为研究对象。采用Boltzman作图法，通过实验测得弓网电弧的光谱信息，进而计算电弧通道的温度。结果表明，由于单次电弧持续时间短又受弓网相对运动的影响，其温度并不很高，且电弧温度随着电弧持续时间的增加而增加。采用盲目反卷积的方法求解307.92 nm谱线的Stark展宽，再根据Stark展宽求得电弧的电子密度，结果表明弓网电弧通道的电子密度和其他种类电弧电子密度在同一数量级上；说明电弧引起的粒子电离效应明显。由此可知光谱法在电弧温度及电弧电离特性的分析中是较为方便和准确的。     

Radiation-Temperature Reference Level in Waveguide Probe Measurement of Electron Plasma Temperature

It is shown that the waveguide probe determinations of electron temperature of shock-heated plasma reported in the literature contain two errors. The major one is due to the use of an incorrect reference level for the plasma radiation temperature; the other is due to the use of an incorrect equation for relating the raw data to the electron plasma temperature. The effects of these errors are examined.