Measurement of density, temperature, and electrical conductivity of a shock-compressed nonideal nitrogen plasma in the megabar pressure range

Kinematic and thermodynamic parameters of shock-compressed liquid nitrogen are measured behind the front of a plane shock wave using plane wave and hemispherical shock wave generators. In these experiments, high values of compression parameters (shock-compressed hydrogen density? ≈ 3.25 g/cm³ and temperature T≈ 56000 K at a pressure of P ≈ 265 GPa) are attained. The density, pressure, temperature, and electrical conductivity of the nonideal plasma of shock-compressed liquid nitrogen are measured. A nearly isochoric behavior of the nitrogen shock adiabat is observed in the pressure range P = 100–300 GPa. The thermodynamics of shock-compressed nitrogen is an alyzed using the model of the equation of state in the quasi-chemical representation (SAHA code) as well as the semiempirical wide-range equation of state developed at the Institute of Experimental Physics. Experimental results are interpreted on the basis of calculations as the fixation of the boundary of transition of shock-compressed nitrogen from the polymer phase to the state of a strongly nonideal plasma at P ≈ 100 GPa, ? ≈ 3.4 g/cm³.     

Evidence of short-range screening in shock-compressed aluminum plasma

We have investigated the angular variation in elastic x-ray scattering from a dense, laser-shock-compressed aluminum foil. A comparison of the experiment with simulations using an embedded atom potential in a molecular dynamics simulation shows a significantly better agreement than simulations based on an unscreened one-component plasma model. These data illustrate, experimentally, the importance of screening for the dense plasma static structure factor.     

Dynamics of the interaction between plasma flows generated by a miniature magnetoplasma compressor and a target

Spectroscopic studies of compression plasma flows generated by a miniature magnetoplasma compressor and of the shock compressed plasma layer formed near a target surface exposed to these flows are reported. The peak electron temperature and density are found to be 3 eV and 1.2⋅10¹⁶ cm⁻³, respectively, in the compressor flow and 4.5 eV and 6.7⋅10¹⁶ cm⁻³ in the shock compressed layer.     

等离子体针放电的振动温度和气体温度研究

大气压等离子体针空气放电产生的低温等离子体由于脱离了真空装置,在工业上具有广泛的应用前景。本文采用等离子体针装置在空气中产生了稳定的大气压等离子体羽,并利用光谱法对等离子体羽的振动温度和气体温度进行了研究。结果发现大气压空气等离子体羽的放电区域分为强光区和弱光区。放电发光信号是宽度为几个微秒的脉冲。研究结果表明等离子体振动温度随空间位置不同在2 500～3 000K范围变化。振动温度在强光区随着远离针尖距离的增大振动温度呈上升趋势,在5mm左右存在极大值,在弱光区随着远离针尖距离的增大振动温度呈下降趋势。与其相似,弱光区放电的气体温度随着远离针尖距离增大,从640K降低到540K。这些结果对大气压空气放电的工业应用具有重要意义。     

Measurement of low electronic temperature in weakly magnetized plasma

The measurement of low electronic temperature by radiofrequecy quadrupole probe has been obtained in weakly magnetized argon plasma. The comparison with the experimental results in unmagnetized plasma confirm that the probe act as an interferometer for the electrostatic waves.     

Elastic-plastic deformation and fracture of shock-compressed single-crystal and polycrystalline copper near melting

The Hugoniot elastic limit, the yield strength, and the spall strength of polycrystalline M1 copper and single-crystal (110) and (111) copper are determined during shock compression up to 8 GPa in the temperature range 20–1080°C from an analysis of the free-surface velocity profiles recorded with VISAR laser velocimeter. The measurements show that all copper samples exhibit strong athermal hardening (increase in the Hugoniot elastic limit) near the melting temperature. Copper single crystals have a very low elastic limit in the temperature range up to 600°C, this limit increases sharply as the temperature increases to 1000°C, and it depends on the crystallographic orientation of a single crystal. The temperature dependence of the spall strength has a threshold character for all copper samples. Copper single crystals demonstrate higher resistance to spall fracture; however, near the melting temperature, the difference between the spall strengths of the copper single crystals and M1 copper becomes insignificant, 50% of the initial level.     

脉冲高能准分子激光烧蚀块靶产生等离子体的动力学过程的差分模拟

 利用质量连续性、动量守恒和能量守恒这三个基本方程,研究高能脉冲激光照射块状靶材产生等离子体的物理特性。采用差分法和Pichard迭代法,求解带特定边界条件的流体力学三方程,得出已喷射等离子体的温度、密度和速度的分布的迭代方程,并用计算机进行了数值模拟。     

��ǿ������ƽ�污ĤCu���໥�����е���������ʵ���о�

实验研究了超强激光与平面薄膜Cu靶的相互作用中,在靶背法线方向产生的离子能量分布.实验中采用固体核径迹探测器CR39和Thomson谱仪相结合测量离子能谱.实验中同时测量到了质子和C4+、C3+、C2+和C1+离子.实验结果表明:离子沿着靶背法线方向发射,离子在一定能量处出现截断;在固体核径迹探测器CR39上可以看出碳离子信号比质子信号弱,质子的产额远高于碳离子,质子对碳离子有屏蔽作用;在相同发次中C4+、C3+、C2+和C1+离子随着荷质比的增大,相应离子的截止能增加.     

等离子体源离子注入过程中半圆形碗状样品的两维温度分布

等离子体源离子注入过程(PSII)中样品温度是一个非常重要的参量。由于注入到样品上的能量很大，导致样品温度很高，所以在实验中获知样品的温度分布有着很重要的意义。本文利用热传导方程建立了半圆形碗状样品内部温度升高模型，研究样品内温度演化过程。以注入离子束流作为能量输入项，热辐射为能量损失项，并考虑了热辐射过程中样品的形状因子的影响。考察了离子注入过程中样品上所施加负偏压的脉冲宽度和频率对样品温度分布的影响。研究结果显示，脉冲频率达到一定值后，样品温度不再随频率增加而升高。     

Measurement of the surface resistance of single-crystal copper in the millimeter-wave region at room temperature

Measurements of the surface resistance of single-crystal copper at millimeter wavelengths (35 GHz) indicate the existance of an anomaly of the skin effect at room temperature. The surfaces were prepared in stress-free processes, annealed, and manipulated in purified hydrogen and argon.     

Localized density clumps generated in a magnetized nonneutral plasma

The final, nonlinear, saturated state of the diocotron instability is investigated experimentally in a magnetized, annular, nonneutral plasma. As the wave grows to large amplitude, the plasma is organized into vortices. In the limit of high magnetic fields, and moderate central conductor biases, the diocotron modes compress the plasma into dense (n 3.5n₀) localized clumps. Two-dimensional particle-in-cell computer simulations confirm the physical picture of vortex formation by resonant particle trapping.     

Experimental measurements of the compressibility, temperature, and light absorption in dense shock-compressed gaseous deuterium

Experimental data on the shock compression, temperature, and absorptivity of gaseous deuterium with an initial density close to its value in the liquid state were obtained on a spherical explosion shock-wave generator in a pressure range of 80–90 GPa. The obtained results are compared with the existing experimental and theoretical data.     

Deposition of copper coatings in a magnetron with liquid target

Copper coatings were deposited on monocrystalline Si substrates using a magnetron discharge with a liquid cathode in the metal vapour plasma. During the deposition, the bias voltage in the range from 0 V to–400 V was applied to the substrate. The prepared films were investigated by a scanning electron microscope, and their adhesive properties were studied using a scratch tester. It was demonstrated that the adhesion of the deposited films strongly depends on the bias voltage and varies in a wide range.