HL-2A 装置中利用可见光谱段轫致辐射测量有效离子电荷数

通过测量可见光谱段的轫致辐射(λ=535.1nm)强度,结合等离子体电子密度和电子温度,HL-2A     

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在HL-2A装置上研制了用于测量等离子体密度分布的两套幅度调制微波反射仪。微波反射仪采用时间延迟法。这两套微波反射仪有不同的频率范围(26.5～40GHz和40～60GHz),它们所对应的密度测量范围是(0.84～1.98)×1019m-3和(1.98～4.47)×1019m-3。时间分辨率可达1ms,空间分辨率约为5mm。     

EAST装置低杂波电流驱动效率分析

在EAST上通过分析剩余环电压与低杂波功率之间的关系,计算得到了低杂波电流驱动效率。采用归一化功率,即功率对等离子体电流、电子密度、等离子体大半径以及有效电荷数归一化,将所有数据绘制在同一曲线中,这样可以得到不同等离子体参数下的低杂波电流驱动效率。实验得到低杂波电流驱动效率η₀=(0.5~1.3)×10¹⁹ A.m^-2.W^-1,在等离子体电流I_p=277kA、低杂波功率P_LH=681kW条件下,实验得到长达3s的低杂波全波驱动。     

火药燃气作用下电离种子产生等离子体研究

为研究电离种子在火药燃气作用下产生等离子体的规律，建立了密闭爆发器(定容)条件下电离种子产生等离子体的数学模型，设计了火药燃气作用下电离种子产生等离子体的试验系统。采用某型火炮发射药和不同种类的电离种子分别进行了试验，结果表明：电离种子在火药燃气作用下可以产生等离子体，加入钾盐和铯盐后电子密度分别为2.25×10¹⁸m⁻³ 和4.63×10¹⁸m⁻³，铯盐电离效果优于钾盐。通过试验数据和仿真结果比对，发现它们保持在同一数量级内。     

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In order to study the plasma generation of ionized seeds under the action of gunpowder gas, a mathematical model under the condition of closed bomb (constant volume) was established, and a plasma test system was designed. Experiments were carried out with a certain type of artillery propellant and different kinds of ionized seeds. The results show that the ionized seeds can generate plasma under the action of gunpowder gas, and the electron densities are 2.25×10¹⁸m⁻³ and 4.63×10¹⁸m⁻³ after adding potassium salt and barium salt, respectively. The strontium salt ionization effect is better than the potassium salt. Under the test conditions, the simulation results are roughly in agreement with the test data.     

Experimental study of CF4 conical theta pinch plasmaexpanding into vacuum

Langmuir probe, photodiode, and optical multichannel analyzer (OMA) measurements have been made on a pulsed CF₄ conical theta-pinch plasma. A cloud of CF₄ was puffed into a conical theta-pinch coil, converted to plasma, and propelled into the vacuum region ahead of the expanding gas cloud. At a position 67 cm away from the conical theta-pinch coil, the plasma arrived in separate packets that were about 20 μs in duration. The average drift velocity of these packets corresponded to an energy of about 3 eV. The OMA measurements showed that the second packet contained neutral atomic fluorine as well as charged particles. The electron temperature and ion density in the second packet were 2.0 eV and 1.5×10¹³ cm^-3, respectively. The electron temperature and ion density in the wake plasma were 8.3 eV and 4×10¹¹ cm^-3 , respectively. This device can be used for plasma processing or as a laboratory test of numerical and analytical models of the expansion of plasma into vacuum     

HL-2M 装置 CO2 色散干涉仪研制

研制了一套新型 CO₂ 激光色散干涉仪用于 HL-2M 装置初始放电期间的电子密度测量。该系统采用 基于激光倍频的色散测量原理,能够消除机械振动产生的相位误差。该系统使用全新的调相式信号调制,研发了 相应的数据采集/处理/上传系统。根据实验测量结果表明,CO₂ 激光色散干涉仪和微波干涉仪测量曲线基本一致, 色散干涉仪系统的测量精度约为 2×10¹⁷m⁻³,密度测量上限能达到 10²¹m⁻³。     

HL—1装置等离子体轫致辐射径向分布的测量

采用经钨带灯标准光源标定的多道石英光纤光学系统,测量了HL-1装置等离子体可见光波段轫致辐射功率的径向分布。测得的有效离子电荷数Z_(eff)的径向分布在中心处有最大值。放电过程中电子密度的增大使Z_(eff)降低。不同放电条件下的实验结果表明,用脉冲送气提高电子密度,可使中心弦平均Z_(eff)显著降低,而等离子体电流I_p的增大使Z_(eff)上升。在若干次放电中观测到了MARFE现象。     

Pressure dependence of plasma parameters in medium-vacuum nitrogenarc discharge with the titanium cathode

The plasma properties of a medium-vacuum nitrogen arc discharge from a titanium cathode were studied. The arc chamber use was 400 mm in diameter and 600 mm in length. The cathode diameter and thickness were 64 and 25 mm, respectively. The experimental conditions are given as follows: pressure range=1×10^-3~2×10^-1 torr; N₂ gas flow rate=6 ml/min; arc current=50 A. Electric probe characteristics are measured as a function of pressure and distance from the cathode surface. The analytical results obtained show that the electron energy distribution takes 1-Mx at pressures above 1×10^-2 torr but 2-Mx at pressures under 4×10^-2 torr and that the electron density has a maximum value at a certain pressure. The Ti⁺, Ti⁺⁺, and N ⁺₂ ion spectral intensities are measured as a function of pressure and distance from the cathode surface. On comparison of these results and the electron density, the Ti⁺ spectral intensity turns out to be proportional to that of the electron density. This suggests that the major ion in the plasma volume is of the Ti⁺ species     

A two-component model for the electron distribution function in ahigh-current pseudospark or back-lighted thyratron

Temperature, energy, and densities of two electron distribution function components, including an isotropic bulk part and an anisotropic beam, are analyzed for a hydrogen pseudospark and/or back-lighted thyratron switch plasma with a peak electron density of 1-3×10¹⁵ cm^-3 and peak current density of ≈10⁴ A/cm². Estimates of a very small cathode-fall width during the conduction phase and high electric field strengths lead to the injection of an electron beam with energies ⩾100 eV and density of 10¹³-10¹⁴ cm^-3 into a Maxwellian bulk plasma. Collisional and radiative processes of monoenergetic beam electrons, bulk plasma electrons and ions, and atomic hydrogen are modeled by a set of rate equations, and line intensity ratios are compared with measurements. Under these high-current conditions, for an initial density n_H2=10¹⁶ cm^-3 and electron temperature of 0.8-1 eV, the estimated beam density is ≈10¹³ -10¹⁴ cm^-3. These results suggest the possibility of producing in a simple way a very high-density electron beam