真空中微波等离子体喷流电子数密度分布规律实验研究

为了准确诊断真空中微波等离子体喷流的电子数密度，利用统一的发射和单郎缪尔探针测量等离子体的空间电位，再测量等离子体的电流-电压特性曲线.根据空间电位测量结果，在等离子体的电流-电压特性曲线上能准确地获取饱和电流，从而处理出电子数密度.最后的诊断实验表明，当真空环境压强为2—6 Pa、等离子体发生器以60 W以下的微波功率击穿流量范围是42—106 mg/s的氩气时，所产生的微波等离子体喷流中电子数密度分布在1×10¹⁶—7.2×10¹⁶/m³范围内.     

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}     

微波电子回旋共振等离子体增强化学气相沉积法沉积氟化非晶碳薄膜的研究

使用三氟甲烷和苯的混合气体,利用微波电子回旋共振等离子体增强化学气相沉积法制备了F/C比在0.11—0.62之间的α-C∶F薄膜.研究了微波功率对薄膜沉积和结构的影响,发现微波功率的升高提高了薄膜的沉积速率,降低了薄膜的F/C比,也降低了薄膜中CF和CF₃基团的密度,而使CF₂基团的密度保持不变.在高微波功率下可以获得主要由CF₂基团和C=C结构组成的α-C∶F薄膜.薄膜的介电频率关系(1×10³—1×10⁶Hz)和损耗频率关系(1×10²—1×10⁵Hz)均呈指数规律减小,是缺陷中心间简单隧穿引起的跳跃导电所致.α-C∶F薄膜的介电极化主要来源于电子极化 关键词： 氟化非晶碳薄膜 ECR等离子体沉积 键结构 介电性质     

电子回旋共振氩等离子体中亚稳态粒子数密度及电子温度的测量

测量了电子回旋共振（ECR）氩等离子体中Ar的1s₅亚稳态粒子数密度，在气压 为02—0 8 Pa、功率为500—700W的范围内，利用吸收光谱法测量了Ar原子8115 nm谱线的吸收强 度，得到1s₅亚稳态粒子数密度为1×10¹⁵—4×10¹⁵ m ^-3.本文综合考 虑基态和1s₅亚稳态粒子的激发对Ar发射谱线强度的贡献后，用两条发射谱线强 度之比得 到电子温度.结果表明，计入了1s₅亚稳态激发的贡献后，所得到的电子温度与 只考虑基态的贡献得到的电子温度相比存在较大的差别. 关键词： 光谱法 亚稳态粒子数密度 电子温度 ECR等离子体源     

MW-ECR PE-UMS等离子体特性及对Zr-N薄膜结构性能的影响

采用静电探针技术对微波电子回旋共振(MW-ECR) 等离子体进行了诊断,利用等离子体增强 非平衡磁控溅射(PE-UMS)法在常温下制备了Zr-N薄膜, 通过EPMA，XRD，显微硬度对膜的 结构和性能进行评价.实验结果表明，随氮气流量增加，总的等离子体密度从807×10⁹c m^-3增加到831×10⁹cm^-3然后逐渐减小为752×10 ⁹cm^-3；而N₂⁺密度则从312×10^{8< /sup>cm-3线性递增到335×109cm-3；电子温度变化 不大.对薄膜而言，随N₂+密度增大，样品中氮含量增加，而晶粒逐 渐变小，当样品中N/ Zr原子比达到14时，薄膜中出现亚稳态的Zr₃N₄相以及非晶相， 在更高氮流量下，整 个薄膜转变为非晶态.与此相应，薄膜硬度由最初的225GPa增大到2678GPa 然后逐渐减 小到1982GPa. 关键词： 氮化锆薄膜 ECR等离子体 磁控溅射 诊断}     

真空中不同极化电磁波在微波等离子体喷流中的衰减特性实验研究

在真空环境中，利用空间反射电磁波测量装置，开展微波等离子体喷流对垂直和水平极化电磁波衰减的实验研究，分析不同极化电磁波在等离子体中衰减的影响因素.实验结果表明：以氩气为工质，真空室中微波等离子体喷流对垂直和水平极化电磁波具有显著的吸收效应.发生器流量、功率以及实验真空度对垂直极化电磁波在等离子体中的衰减影响明显.真空度和发生器功率对水平极化电磁波没有显著影响. 关键词： 等离子体中的电磁波 等离子体基本性质 电磁波     

激光烧蚀Al靶产生的等离子体中辐射粒子的速度及激波

在低真空条件下(5Pa),通过测量脉冲激光烧蚀平面Al靶产生的等离子体辐射谱的时间分辨特征,得到辐射粒子速度的空间分布.在激光脉冲宽度为10ns,烧蚀斑直径为200μm,靶面上功率密度分别为1.91×10¹⁰,5.10×10¹⁰和7.64×10¹⁰W/cm²时,测得辐射粒子Al的速度均在10⁶cm/s量级,且随着靶面径向距离的增大而近似呈指数衰减.在距靶面的相同距离处,激光功率密度的增大反而使速度减小.利用激波模型(shockwave model)较好地解释了实验结果,并得出激波的波面基本为柱对称 关键词： 激光等离子体 平面Al靶 粒子速度分布 激波     

真空环境中等离子体喷流对反射电磁波衰减的实验研究

在真空环境中，利用传输线测量装置，开展微波等离子体喷流对反射电磁波衰减的实验研究.实验结果表明，采用传输线测量方法能够有效地获得等离子体对反射电磁波的衰减；在5GHz附近，以氩气为工质，流量为52.5mg/s时，52W微波功率在真空环境中产生的等离子体喷流能对反射电磁波产生最大的衰减；增加微波功率、降低真空环境压强可以提高等离子体对反射电磁波的衰减；要使等离子体能够对反射电磁波产生最大的衰减，必须选取合适的发生器参数. 关键词： 电磁波在等离子体中的传输 等离子体基本过程 电磁波     

电推力器等离子体喷流对航天器通讯电磁波信号衰减效应

采用时域有限差分法计算了不同特性电推力器等离子体喷流对不同频率通讯电磁波的衰减系数,采用空间透射波法进行了微波等离子体推力器喷流对C波段电磁波衰减的地面测试实验。理论计算和实验诊断结果表明:电推力器等离子体喷流对电磁波的衰减系数随着电磁波频率的升高逐渐减小,随着喷流等离子体频率的升高近似线性增大,随着喷流等离子体碰撞频率的增大呈先增大后减小的趋势;当喷流中等离子体数密度为0.9×1016~1.8×1016m-3时,C波段电磁波的衰减系数为1.5~6.0 dB,电推力器等离子体喷流对通讯信号的衰减效应不可忽略。     

强流电子束碰撞电离背景气体研究

利用数值计算与粒子模拟两种方法,结合实际的实验数据,对高功率微波二极管中相对论电子束与背景气体相互作用碰撞产生的等离子体密度进行了研究.研究结果表明：碰撞产生的等离子体密度数值计算结果与粒子模拟结果基本一致,背景气压在0.01 Pa—0.05 Pa时,碰撞产生的等离子体密度在4—12×10⁹cm^-3,即便在考虑电子离子复合的情况下,数值计算结果与粒子模拟结果依然符合得很好.另外,粒子模拟结果表明：随着气压的增加,等离子体密度呈现先增大再减小然后又逐渐增大的过程, 关键词： 相对论电子束 等离子体 数值计算 粒子模拟     

Microwave power coupling with electron cyclotron resonance plasma using Langmuir probe

Electron cyclotron resonance (ECR) plasma was produced at 2.45 GHz using 200–750 W microwave power. The plasma was produced from argon gas at a pressure of 2 × 10^???4 mbar. Three water-cooled solenoid coils were used to satisfy the ECR resonant conditions inside the plasma chamber. The basic parameters of plasma, such as electron density, electron temperature, floating potential, and plasma potential, were evaluated using the current–voltage curve using a Langmuir probe. The effect of microwave power coupling to the plasma was studied by varying the microwave power. It was observed that the optimum coupling to the plasma was obtained for ~ 600 W microwave power with an average electron density of ~ 6 × 10¹¹ cm^???3 and average electron temperature of ~ 9 eV.     

射频电感耦合夹层等离子体中的模式转换

本文利用微波相位法和光谱诊断法, 研究了ICP放电等离子体在圆台状夹层等离子体中E模和H模相互转换的物理现象. E模和H模的之间转换过程是一个瞬间突变的, 转换点的输入功率随真空室压强的变化而变化. H模向E模转换的阈值功率低于E模向H模转换的值, 等离子体参数随输入功率变化曲线类似于铁磁物质中的磁滞回线. Ar II 408.2 nm谱线的强度的变化规律和电子密度随功率变化的规律基本一致. 通过本实验可以获得一种电子密度范围为3.85×10¹¹ cm^-3 < n_e < 4.68× 10¹¹ cm^-3, 外表面积为0.3 m², 厚度为2 cm稳定工作的等离子体源.     

OH number densities and plasma jet behavior in atmospheric microwave plasma jets operating with different plasma gases (Ar,Ar/N<Subscript>2</Subscript>, and Ar/O<Subscript>2</Subscript>)

OH radical number density in multiple atmospheric pressure microwave plasma jets is measured using UV cavity ringdown spectroscopy of the OH (A–X) (0–0) band at 308 nm. The plasma cavity was excited by a 2.45 GHz microwave plasma source and plasma jets of 2–12 mm long were generated by using three different plasma gases, argon (Ar), Ar/N₂, and Ar/O₂. Comparative characterization of the plasma jets in terms of plasma shape, stability, gas temperature, emission intensities of OH, NO, and N₂, and absolute number density of the OH radical was carried out under different plasma gas flow rates and powers at various locations along the plasma jet axis. With three different operating gases, the presence of OH radicals in all of the plasma jets extended to the far downstream. As compared to the argon plasma jets, the plasma jets formed with Ar/N₂ and Ar/O₂ are more diffuse and less stable. Plasma gas temperatures along the jet axis were measured to be in the range of 470–800 K for all of the jets formed in the different gas mixtures. In each plasma jet, OH number density decreases along the jet axis from the highest OH density in the vicinity of the jet tip to the lowest in the far downstream. OH density ranges from 1.3 × 10¹² to 1.1 × 10¹⁶, 4.1 × 10¹³ to 3.9 × 10¹⁵, and 7.0 × 10¹² to 4.6 × 10¹⁶ molecule/cm³ in the Ar, Ar/N₂, and Ar/O₂ plasma jets, respectively. The OH density dependence on plasma power and gas flow rate in the three plasma jets is also investigated.     

Expansion dynamics of atmospheric pressure helium plasma jet in ambient air

In this work, the expansion dynamics of a helium plasma jet in ambient air is examined. By using a fast imaging technique, the expansion of plasma jet from glass nozzle to air is captured which is in the form of plasma bullet propagating into the air. To understand the plasma bullet travel path from glass nozzle to plasma jet tip a drag force model is used. Moreover, the spatial variation of plasma density along the plasma jet length is estimated using drift velocity, plasma jet current and the cross-sectional area of the plasma jet. It is observed that the slight increase in plasma density is due to the combined effect of reduction of drift velocity, plasma jet current, and jet cross-sectional area. The obtained plasma density from glass nozzle to jet tip is in the range of (0.069-5.96) × 10¹² cm⁻³. The above parameters can be of the essence in biological and industrial applications.     

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%).     

悬浮型微波共振探针在电负性容性耦合等离子体中电子密度的测量

本文首先利用悬浮型微波共振探针测量了Ar等离子体的电子密度,并与朗缪尔双探针的测量结果进行了比较,表明了微波共振探针在低密度等离子体测量的可行性.对40.68 MHz单射频容性耦合Ar/SF₆和SF₆/O₂等离子体的测量结果表明:电负性气体SF₆掺入Ar等离子体显著降低了等离子体电子密度,但随着增加SF₆的流量,电子密度表现为缓慢下降;而O₂掺入SF₆等离子体中,电子密度则随着O₂流量的增加表现为持续的下降.另外,40.68 MHz/13.56 MHz双频激发的SF₆/O₂容性耦合离子体的电子密度并不随低频功率的变化而变化.本文对上述的实验现象进行了初步的解释.