大气压下电晕电离层离子运动规律的实验研究

对大气压下电晕电离层的离子运动规律进行了实验研究。实验结果表明: 在电晕放电的流光或辉光放电区域, 电离电场强度、注入功率密度、电离能密度等参量对等离子体输运项的影响程度仅在1 个数量级内; 在电离能密度达到0. 4mJ•cm^{- 3} , 气体速度从1. 5m•s^{- 1} 提高到25m•s^{- 1} 时, 离子输运率相应从5. 4× 10⁸ cm^{- 3}•s^{- 1} 增加到8×10¹⁰ cm^{- 3}•s^{- 1} , 提高了近2 个数量级。带电粒子的动量对离子浓度及输运的影响远大于电离电场强度、注入功率密度等的影响。     

高气压强电场电离过程中的离子浓度分布规律

研究了高气压强电场电离区域的离子浓度分布的连续性方程, 对电离区域的电离物的产生、消失和输运进行了研究。通过采用电离放电增加了输入能量密度、G 值、电离占空比等, 从而提高了离子产生率。通过外加电场和离子“雪崩”头部的本征电场的叠加作用, 离子被束缚在放电通道中。对离子施加垂直电场方向的作用力, 就能把电场中的等离子体成束输送出去。已经能够做到有效体积仅为1cm³的等离子体源, 输运等离子体率达到 10¹² cm^{- 3}•s^{- 1}。     

激光辐照固体靶产生等离子体反冲研究

提出一种通过诊断等离子体反冲动量来计算激光加载产生冲击压强的方法. 当强激光辐照固体靶表面时, 所产生的高速喷射的等离子体对靶具有反冲作用, 通过诊断等离子体反冲动量的变化可以计算激光辐照固体靶产生的冲击压强变化. 本文利用辐射流体力学软件研究了这种诊断方法, 模拟采用的激光功率密度为5×10¹²-5×10¹³ W/cm², 激光脉宽选取纳秒量级. 模拟结果表明该方法是有效且可行的.     

355 nm激光光电离甲醛飞行时间质谱的研究

利用脉宽为5 ns脉冲Nd: YAG 355 nm激光在功率密度为10¹¹–10¹² W/cm²条件下实现了甲醛含水团簇多光子电离, 并用飞行时间质谱对其电离产物和电离过程进行了研究. 实验中观测到了甲醛的质子化团簇系列 (CH₂O)_nH⁺(n=1–4), 甲醛的去质子化团簇系列(CH₂O)_nCHO⁺ (n=1–3), 以及两个起源于H₂CO去质子和质子化的含水团簇系列HCO⁺(H₂O)_n(n=1,3,5)和H₃CO⁺(H₂O)_n(n=1,3,5), 并对其中的一些团簇结构构型进行了猜测. 研究在不同的激光功率密度下甲醛团簇质谱峰的变换情况, 当激光密度达到9.3× 10¹¹ W/cm², 开始出现CH₂O和H₂O本体及其光致碎片的信号, 但对应的各质量峰没有明显地分辨开, 而是以包络的形式出现, 这是激光电离产生高能离子释放的一种表现, 提出认等离子体动力学鞘层加速机制(模型)来解释高能离子形成的物理机制. 关键词： 甲醛 团簇 飞行时间质谱 激光电离     

ZBLAN玻璃中Pr3+掺杂离子3P0和1D2能级的发光特性和寿命

对ZBLAN氟锆酸盐玻璃中Pr³⁺掺杂离子³P₀和¹D₂能级的寿命和发光特性进行了较详细的光谱学研究。首先测量了两种掺杂浓度(质量分数分别为1×10^-3,5×10^-3)的Pr³⁺:ZBLAN玻璃的吸收光谱,然后运用时间分辨激光光谱技术测量了³P₀和¹D₂能级在激光单光子共振激发下的荧光发射谱和能级寿命。将不同荧光发射谱带的强度和文献报道的Judd Ofelt理论计算辐射跃迁几率数值做了比较分析,证明了文献中理论计算结果的可靠性。由于浓度猝灭效应,在相同的激发条件下,掺杂浓度为1×10^-3样品的荧光发射强度明显大于5×10^-3样品的荧光发射强度。但是从我们的测量结果看,掺杂浓度对³P₀和¹D₂ 的能级寿命值无显著影响。掺杂浓度为1×10^-3时,Pr³⁺离子³P₀和¹D₂能级的寿命值分别为46,322μ_s。     

超冷铷铯极性分子振转光谱的实验研究

利用激光冷却俘获技术在双暗磁光阱中获得高密度的超冷铷原子和铯原子,通过光缔合方法制备超冷铷铯极性分子.采用共振增强双光子电离技术探测基三重态a³∑⁺的铷铯分子,产率约为10⁴/s.通过改变缔合光频率,获得（2）0⁺,（3）0^-,（2）0^-等分子态的高分辨振转光谱,拟合得到相应的转动常数分别为0.00349 cm^-1,0.00649 cm^-1,0.00372 cm^-1.     

电子束产生大尺度等离子体过程的数值模拟研究

建立了一个四组分一维混合模型，对电子束注入大气产生大尺度等离子体的过程进行了数值模拟.结果表明了能量为140keV、流强为50mA/cm²的注入电子束，可以产生线度为0.5m，密度为10¹²cm^-3量级的大气环境下等离子体.电子束所伴随的空间电荷效应由于等离子体的产生会很快消失，不影响后续的等离子体产生过程.电子束注入流强主要影响产生等离子体的密度，而电子束能量则同时影响其空间线度和密度. 关键词： 电子束 碰撞 电离     

部分电离金属钛和银等离子体输运性质的计算

金属等离子体的组分为计算热力学、光学和辐射输运特性研究提供了基本的输入参数.为获得此参数,本文用部分电离等离子体模型,在考虑金属发生三次电离,以及电子与中性粒子的极化作用、离子与离子之间、电子与离子之间、电子与电子之间库仑相互作用下,计算得到了等离子体组分,进而用线性响应理论计算了金属钛和银的电导率.并与已有的实验数据进行了比较,验证了模型的可靠性.在此基础上进一步预测了密度在0.001—2.0 g/cm³、温度在1.5×10⁴—2.5×10^{4关键词： 等离子体 线性响应理论 电离度 输运系数}     

约化场强对氮-氧混合气放电等离子体演化特性的影响

采用零维等离子体动力学模型,计算了不同约化场强条件下N₂/O₂放电等离子体的演化特性.结果表明,平均电子能量与约化场强有着近似的线性关系,在约化场强为100 Td时,平均电子能量约为2.6 eV、最大电子能量达35 eV;约化场强是影响电子能量函数分布的主要因素.气体放电过程结束后,振动激发态氮分子的粒子数浓度不再变化,电子激发态的氮分子、原子和氧原子的粒子数浓度达到一峰值后开始降低;放电结束后的氧原子通过复合反应生成臭氧.约化场强升高,由于低能电子减少的影响,振动激发态氮分子的粒子数浓度降低,当约化场强由50 Td增加75 Td,100 Td时,粒子数浓度由3.83×10¹¹ cm^-3降至1.98×10¹¹ cm^-3和1.77×10¹¹ cm^-3,其他粒子浓度则相应增大. 关键词： 等离子体 约化场强 粒子演化 数值模拟     

超短超强激光脉冲辐照超薄碳膜电离状态研究

为了进一步理解极端条件下物质的电离特性, 特别是超短超强激光脉冲辐照超薄靶时等离子体的形成与分布, 本文以超薄碳膜为例, 细致研究了超短超强激光脉冲辐照下原子的离化过程. 分析和比较了强激光场直接作用电离和靶内静电场电离等两种场致电离形式, 在碰撞电离可以忽略的情况下, 发现更多的电离份额是来自靶内静电场的电离方式. 研究了激光脉冲强度对电离的影响, 发现激光脉冲强度越强, 电离速度越快, 产生的高价态离子所占比例也越高.当激光强度为1×10²⁰ W/cm²时, 尽管该强度高于电离生成C⁺⁶所需要的激光强度阈值, 但该激光脉冲并不能将整个靶电离成C⁺⁶离子, 对此本文进行了详细的分析. 在研究激光脉冲宽度的影响时, 发现激光脉宽越小, 电离速度越快, 但越小的激光脉冲电离获得的高价态离子越少.     

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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.     

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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The multichannel bremsstrahlung measurement system on HL-2A tokamak has been using to observe the intensity of visible (535.1nm) bremsstrahlung radiation. Combined the intensity with plasma electron density and electron temperature, the effective ion charge measurements can be obtained on HL-2A tokamak. The 1×10¹⁹m⁻³ to4×10¹⁹m⁻³ experimental results show that when the plasma electron density increases from 1×10 m to 4×10 m , the effective ion charge number changes from 5 down to around 2. The bremsstrahlung radiation signal intensity is proportional to the quadratic plasma density. When the electron density is higher than 3×10¹⁹m⁻³, the multichannel bremsstrahlung measurement system can collect sufficient signal through the plasma, which enables the measurement of effective ion charge radial profile.     

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     

S—Ka频段电磁波在等离子体中传输特性的实验研究

在感应耦合等离子体风洞上开展了等离子体中电磁波传输特性实验研究,获得了不同频率电磁波在等离子体中的传输衰减.通过微波诊断技术,获得了等离子体射流的电子数密度和碰撞频率.通过矢量网络分析仪和标准增益天线组成的电磁波传输特性测试系统,获得了电磁波经过等离子体之后的衰减,研究了电子数密度范围7.0×10~(10)-1.0×10~(13)cm~(-3)、等离子体碰撞频率在109 Hz量级的等离子体对2.6—40 GHz不同频率电磁波传输特性的影响,分析了经典传输理论和薄层理论预测结果与实验结果的差异.该实验工作为等离子体中电磁波传输特性的理论研究和数值仿真提供了基础数据.     

温稠密钛电导率计算

温稠密物质是惯性约束核聚变、重离子聚变、Z箍缩动作过程中物质发展和存在的重要阶段. 其热力学性质和辐射输运参数在聚变实验和内爆驱动力学模拟过程中有至关重要的作用. 本文通过建立非理想Saha方程, 结合线性混合规则的理论方法模拟了温稠密钛从10^-5-10 g·cm^-3, 10⁴ K到3×10⁴ K区间的粒子组分分布和电导率随温度密度的变化, 其中粒子组分分布由非理想Saha方程求解得到. 线性混合规则模型计算温稠密钛的电导率时考虑了包括电子、原子和离子之间的多种相互作用. 钛的电导率的计算结果与已有的爆炸丝实验数据相符. 通过电导率随温度密度变化趋势判断, 钛在整个温度区间, 密度0.56 g·cm^-3时发生非金属相到金属相相变. 对于简并系数和耦合系数的计算分析, 钛等离子体在整个温度和密度区间逐渐从弱耦合、非简并状态过渡到强耦合部分简并态.     

Photo-ionized lithium source for plasma accelerator applications

A photo-ionized lithium source is developed for plasma acceleration applications. A homogeneous column of lithium neutral vapor with a density of 2×10^15-3 is confined by helium gas in a heat-pipe oven. A UV laser pulse ionizes the vapor. In this device, the length of the neutral vapor and plasma column is 25 cm. The plasma density was measured by laser interferometry in the visible on the lithium neutrals and by CO₂ laser interferometry on the plasma electrons. The maximum measured plasma density was 2.9×10 ¹⁴ cm^-3, limited by the available UV fluence (≈83 mJ/cm²), corresponding to a 15% ionization fraction. After ionization, the plasma density decreases by a factor of two in about 12 μs. These results show that such a plasma source is scaleable to lengths of the order of 1 m and should satisfy all the requirements for demonstrating the acceleration of electrons by 1 GeV in a 1-GeV/m amplitude plasma wake     

A cold thermionically emitting dusty air plasma formed by radiativeheating of graphite particulates

Formation of an atmospheric pressure dusty air plasma is explored experimentally in this paper. The plasma is created by seeding an air flow with graphite particles and irradiating the particulates with a focused CO₂ laser beam. The graphite particles are, thus, heated to thermionically emitting temperatures, and average particle temperatures and average particle number densities are measured. The presence of charges is inferred both from these measured quantities using a simple theoretical transient model, and experimentally by applying a dc bias across the irradiated region. It is found that an electron density of ~6.7 × 10⁵ cm^-3 (6.7 × 10¹¹ m^-3) can be produced at steady state in the presence of O₂. This value can be increased to 3.6 × 10⁷ cm^-3 (3.6 × 10¹³ m ^-1) in the ideal case where an electron attachment to O₂ is suppressed and where a lower work function particulate is used     

Spectroscopic investigation of a low current arc in pure fluorine

A pure fluorine 10-A DC arc has been operated in an Al₂O₃ tube of 18 mm diameter at atmospheric pressure. This arc was used to perform radially resolved spectroscopic end-on measurements in the visible and UV-spectral regions. An excitation temperature of 7800 K on the arc axis was determined from the intensity of atomic fluorine lines, and an ion density of 1.7×10 ²¹ m^-3 was determined from the half-width of the contamination line H_β. A Boltzmann plot of the affinity continuum in the UV-spectral region yields two groups of electrons. A group of hot electrons is characterized by a temperature that agrees with the excitation temperature, and a group of cold electrons has a temperature in accordance to the gas temperature of 4000 K. The absolute intensity of the affinity continuum gives and electron density of 1.3×10²⁰ m^-3 on the arc axis, which is lower than the density of both positive and negative ions in the discharge. From the difference between the electron and gas temperature, an elastic collision cross section between the electrons and F-atoms of 2×10^-20 m² is determined