Waveguide—surfatron型表面波等离子体源的特性研究

报道了所研制的Waveguide-surfatron型表面波等离子体源的特性,理论计算表明,激发表面波模式为m≥1模,在放电室中电磁场均匀性与等离子体的密度有关。实验结果指出,采用Ar气放电,在气压为10-100Pa,微波功率800-1000W的范围内可形成大面（体）积（直径为160mm)等离子体,其电子温度为1-4eV,等离子体密度为10^10-10^11cm^-3量级,实测的等离子体密度与理论计算值基本吻合。     

He-Ar潘宁过程对表面波等离子体柱功率的影响

由单极驱动的表面波等离子体(Surface-wave-sustained plasma,SWP)是近年发展起来的一种低气压、高密度等离子体,这种技术非常适用于等离子体天线等领域.本文介绍了一种简易实用的SWP源,研究了He-Ar组成的潘宁气体对于表面波等离子体柱的放电起始功率及维持功率的影响.测试了不同潘宁气体配比时的等离子体密度和等离子体温度.研究结果表明,应用合适配比的潘宁气体对于等离子体特性有很大影响,它可以有效地降低放电起始功率和放电维持功率,提高等离子体密度,等离子体温度略降低.     

宽气压范围内裂缝天线等离子体特性研究

给出了气压为10～28000Pa时,环形倾斜裂缝天线等离子体源的放电特性.实验表明,该源在气压为10～2600Pa范围内是大体积表面波放电,并且在气压为10和230Pa时清楚地观察到裂缝天线附近石英管内的等离子体有较明显的8个瓣和12个瓣(表面波模式可确定为m=4和m=6);当气压升高到4000～6000Pa时,在石英管的底端和不锈钢真空室交界处激励起直径约为12cm的高密度等离子体椭球(1011cm-3量级);在气压为11000～14000Pa时,发现等离子体有明显的涡动现象;而当气压上升到20000Pa以上,等离子体有丝状结构出现.     

He—Ar潘宁过程对表面波等离子体的影响

潘宁过程可以有效地降低直流、低频放电中的放电起始电压.关于射频放电,特别是表面波等离子体中的潘宁过程的研究,目前还很少有报道.本文介绍了一种由Ro-box装置激发的SWP源,通过实验方式研究了此装置产生的表面波等离子体柱中的He-Ar潘宁过程对其物理性质的影响.结果表明,合适配比的潘宁气体对于表面波等离子体柱特性有很大影响,它可以有效地降低放电起始功率和放电维持功率,延长等离子体柱长度,提高等离子体密度等;在此过程中电子温度略降低.本研究为在表面波等离子体应用中获取合适的等离子体参量提供了新的途径.     

小型腔式微波离子源的等离子体产生及引出特性

研制了一种用石英管制作的小型腔式微波离子源，该腔套在石英管的一端，封装两电极引出系统。该离子源利用腔激发起的表面波在石英管内产生等离子体柱。在微波频率为2．45GHz、输入功率为93W时，氮的引出离子流密度可高达91．7mA／cm2。这种表面波放电等离子体源具有体积小、结构简单，在宽的压强范围内能产生再生性好、工作十分稳定的等离子体柱（1012～1013cm-3）等特点。还给出了放电的自一致描述以及放电的电子密度与压强、等离子体柱半径和输入功率的关系。     

小型腔式微波离子源的等离子体产生及引出特性

研制了一种用石英管制作的小型腔式微波离子源，该腔套在石英管的一端，封装两电极引出系统。该了源利用腔激发起的表面波在石英管内产生等离子体柱。在微波频率为２．４５ＧＨｚ，输入功率为９３．Ｗ时，氮的引出离子流密度可高达９１．７ｍＡ／ｃｍ２＾２。，这种表面波放电等离子体源具有体积小，结构简单，在宽的压强范围内能产生再生性好，工作十分稳定的等离子体柱等特点。     

宽气压范围内裂缝天线等离子体特性研究

给出了气为10－28000Pa,环形倾斜裂缝天线等离子体源的放电特性,实验表明,该源在气压为10－2600Pa范围内是大体积表面波放电,并且在气压为10和230Pa时清楚地观察到裂缝天线附近石英管内的等离子体有较明显的8个瓣和12个瓣（表面波模式可确定为m=4,和m=6）,当气压升高到4000－6000Pa时,在石英管的底端和不锈钢真空室交界处激励起直径约为12cm的高密度等离子体椭球（10^11cm^-3量级）,在气压为11000－14000Pa时,发现等离子体有明显的涡动现象,而当气压上升到20000Pa以上,等离子体有丝状结构出现。     

表面波等离子体天线的能量衰减系数研究

根据功率平衡原理,得到了表面波等离子体天线中等离子体柱长度、等离子体密度与馈入功率的关系,导出了表面波等离子体天线中能量衰减系数沿轴向分布.实验测得充气压强为0.5Pa,6Pa和40Pa时等离子体柱长度、馈入功率和等离子体密度,得到能量衰减系数的实验值.结果表明,等离子体柱上z点的能量衰减系数为该点到等离子体柱顶端距离的倒数,实验所测结果与理论符合得很好.该结论对研究表面波等离子体天线的激励和维持十分重要.     

介质管内等离子体表面波传播特性研究

研究了同轴对称表面波沿介质管内的等离子体轴向传播的特性,导出了介质管内外的电磁场表达式,数值计算并仿真模拟了等离子体密度、信号频率、介质管内径、碰撞频率等因素对表面波在等离子体中传播的影响。结果显示,密度在1016m-3~1017m-3量级的等离子体更接近金属导体,介质管半径在11 mm~19 mm之间更有利于表面波的传播,而碰撞频率的影响并不明显。此结果对实验具有重要的指导意义。     

新型表面波等离子体源的诊断及不同工艺条件下的等离子体特性

表面波等离子体(Surface-wave-sustained plasma,SWP)是近年发展起来的一种新型低压、高密度等离子体。应用这种技术,很容易实现镀膜过程中的离子束辅助沉积(IBAD),从而制备出性能优异的类金刚石薄膜(DLC)。本文介绍了一种新型的SWP源,说明了朗缪尔探针等离子体诊断的基本原理,研究了微波功率、靶电压、真空度等对等离子体特性的影响。测试了不同工艺条件下的等离子体密度,电子温度,等离子体电位,悬浮电位。研究结果表明,微波功率、靶电压和真空度等参数对等离子体特性具有重要的影响。结果同时表明,这种表面波等离子体源即使在0.85 Pa的真空度下也能够产生高达1.87×1011cm-3的电子密度(在2.8 Pa可达2.1×1012cm-3)。     

Study of microwave components for an electron cyclotron resonance source: Simulations and performance

A high power (2 kW, CW) magnetron-based microwave system operating at 2.45 GHz has been designed, tested, characterized, and used to produce plasma. The system consists of a microwave source, an isolator, a directional coupler, a three-stub tuner, a high voltage break, a microwave vacuum window, and a microwave launcher. These microwave components were simulated using microwave studio software. The low power and full term characterization of the microwave system has been done using vector network analyzer. The system was tested for 2 kW continuous wave of microwave power using glass-water load. The microwave system has been developed to study the microwave interaction with plasma at different operation regimes (Gases: Nitrogen, argon and hydrogen; Gas pressure : 10^?5–10^?3 mbar; Microwave power : 300–1000 W; Magnetic field: 875–1000 G) and to extract the proton beam current with hydrogen produced plasma. A plasma density ～5 × 10¹¹ cm^?3 and average electron temperature of ～13 eV was obtained. This article describes various aspects of the microwave system including design, fabrication, characterization and performance studies of the microwave components.     

Optical emission patterns and microwave field distributions in a cylindrical microwave plasma source

A cylindrical high density (10¹² cm⁻³) large volume (32 cm in diameter and 50 cm in length) homogeneous argon plasma has been produced by a microwave with a frequency of 2.45 GHz and a power of 900 W without a magnetic field. The plasma source is based on a ring shaped rectangular waveguide with eight equally spaced slots in its inside wall. Several optical emission patterns are observed on different conditions and the microwave field is measured by a movable antenna, which showed a clear relationship between the optical emission patterns and the electron field distributions. A mode transition, from a TE_8j mode to a TE_16j mode, occurs when the gas pressure increases from 660 to 1000 Pa. And there is an optical emission pattern when the microwave power decreases from 900 to 300 W. All these phenomena are described in detail and analyzed according to the interactional theory of electrons in plasma with microwave.     

用于大面积材料表面改性研究的微波等离子体源

介绍了环形狭缝波导天线等离子体源的原理和结构。采用微波单探针测量了无等离子体情况下环形波导狭缝天线内的电场分布，利用Langmuir双探针测量了该源的氩等离子体的特性，结果表明在微波功率为200～600W，运行气压为40～600Pa范围内，电子温度可达0.5～3eV，离子密度最高达6×1010cm-3在气压为100Pa，等离子体的直径为16cm范围内，其不均匀性不超过25％。     

Uniform coating of CVD diamond on metallic wire substrates

Diamond was coated onto wire substrates of various transition metals (Mo, W or Ti) of 0.5 mm diameter by the microwave plasma CVD method from a gas mixture of the CO–H₂ system. The CVD conditions for a uniform diamond coating were microwave power, 750–1100 W; total pressure, 2000 Pa; total flow rate, 200 ml min-1; CO concentration, 5 vol%; treatment time, 5 h. The wire substrates were mounted vertically or horizontally on a pyrophyllite susceptor, which was placed parallel to the irradiation direction of microwave power. Homogeneous and fine-grained diamond film was prepared on the whole surface of horizontal W wire substrate with a wire height of 2 mm from the susceptor. To obtain a dense diamond coating, the height has to be as low as possible in the plasma region, where the plasma density is higher at lower substrate temperature. Low pressure and high microwave power were suited for fine-grained coating. Diamond deposition rate was found to be more dependent on pressure than substrate temperature. As the pressure increased, a glassy carbon film was formed instead of diamond. This revised version was published online in November 2006 with corrections to the Cover Date.     

Hydrogen atom density in a solar plasma reactor

A density of neutral hydrogen atoms was systematically measured in the MESOX solar plasma reactor at different MW powers and flow rates. The H-atom density was measured by a gold fibre optics catalytic probe. The H-atom density was in general increasing with increasing MW power. At a pressure of 40 Pa and a power of 500 W it was about 3.5 × 10²¹ m⁻³ and at a power of 1000 W it was about 4.1 × 10²¹ m⁻³. A degree of dissociation of hydrogen molecules was between 3% and 20% depending on pressure and power. A maximum degree of dissociation was obtained at a pressure of 40 Pa and 1000 W, while the lowest one at 130 Pa and 500 W.     

A Simulator for Producing of High Flux Atomic Oxygen Beam by Using ECR Plasma Source

In order to study the atomic oxygen corrosion of spacecraft materials in low earth orbit environment, an atomic oxygen simulator was established. In the simulator, a 2.45 GHz microwave source with maximum power of 600 W was launched into the circular cavity to generate ECR (electron cyclotron resonance) plasma. The oxygen ion beam moved onto a negatively biased Mo plate under the condition of symmetry magnetic mirror field confine, then was neutralized and reflected to form oxygen atom beam. The properties of plasma density, electron temperature, plasma space potential and ion incident energy were characterized. The atomic oxygen beam flux was calibrated by measuring the mass loss rate of Kapton during the atomic oxygen exposure. The test results show that the atomic oxygen beam with flux of 1016-1017 atoms-cm-2·s-1 and energy of 5-30 eV and a cross section of φ80 mm could be obtained under the operating pressure of 10-1-10-3 Pa. Such a high flux source can provide accelerated simulation tests of mater     

微波等离子体中OH自由基的光腔衰荡光谱诊断

搭建了一套以可调谐半导体激光器为光源的连续波光腔衰荡光谱装置,将其与微波等离子体装置结合,对等离子体中的OH自由基进行了原位定量测量,同时考察了OH自由基数密度随气压和微波功率的变化情况.实验结果表明:以氮气为工作气体,在(0.66～3.99)×103Pa范围内,随着气压的升高,OH自由基数密度先增加后降低,在1.995×103Pa时达到最大值;随着微波功率的升高OH自由基数密度逐渐增加.     

Hydrogen-free diamond-like carbon films prepared by microwave electron cyclotron resonance plasma-enhanced direct current magnetron sputtering

Hydrogen-free diamond-like carbon (DLC) films were prepared by means of microwave electron cyclotron resonance plasma enhanced direct current magnetron sputtering. To study the influence of enhanced plasma on film fabrication and properties, the structures as well as mechanical and electrical properties of these films were studied as a function of applied microwave power. Results showed that higher microwave power could induce higher plasma density and electron temperature. The hardness increased from 3.5 GPa to 13 GPa with a variation of microwave power from 0 W to 1000 W. The resistivity showed a drastic increase from 4.5 × 10⁴ Ωcm at 0 W to 1.3 × 10¹⁰ Ωcm at 1000 W. The variation of the intensity ratio I(D)/I(G) and the position of the G-peak of the DLC films with respect to changes in microwave power were also investigated by Raman spectroscopy.     

Oxygen atom density in microwave oxygen plasma

We determined the density of neutral oxygen atoms in microwave plasma using a fiber-optics catalytic probe (FOCP). Plasma was created within a quartz tube with an outer diameter of 5 cm by a 2.45 GHz microwave generator with an output power up to 1000 W. The oxygen flow was varied between 4 and 20 l/h. The O-atom density was found to increase monotonically with the increasing discharge power, and it decreased with the increasing flow rate. The degree of dissociation of oxygen molecules in the plasma column depended largely on the flow rate. At the oxygen flow of 4 l/h, it was about 18% but it decreased to about 6% at the flow of 20 l/h.     

用于电离层环境模拟器的ECR等离子体源

为了经济地考验空间电离层等离子体对处于其中的飞行器表面的作用,需要在地面建立等离子体环境模拟器。本文就是为空间电离层环境模拟器研制的扩散型极低气压、低电子温度和极低密度的紧凑型电子回旋共振等离子体源的研制。结果显示在等离子体源下游50cm处,在10-2～10-3Pa范围内获得了电子温度低于5eV,密度在104～106cm-3范围内的较为均匀的等离子体束流,基本满足了空间环境模拟实验的需要。