Electron Cyclotron Harmonic Wave Heating in Tokamak Plasmas with Different Polarization Modes

Electron cyclotron heating on HL-2A has been simulated by TORAY-GA with a second harmonic extraordinary wave and a fundamental ordinary wave. The results show that the wave absorption of the second harmonic extraordinary wave is better than that of the fundamental ordinary wave. In order to understand the interaction mechanism between electrons and the two different polarization modes, the energy exchange between electrons and the two modes are theoretically analyzed, and it is found that the coupling intensity described by the Bessel function and different polarizations of the two modes are the main reasons leading to the above phenomenon. The theoretical results of this study fit well with the simulated and numerical results.

Relative Irradiance Measurement and Bonding Configurations of Amorphous Fluorinated Carbon Films Deposited by Electron Cyclotron Resonance Plasma

a-C:F films are deposited by microwave electron cyclotron resonance (ECR)plasma chemical vapor deposition (CVD) using trifluoromethane (CHF3) and benzene (C6H6) as source gases at different microwave powers. The radicals in plasma originating from source gases dissociation are analyzed by relative irradiance measurement. The bonding configurations and binding state of a-C:F films are measured with Fourier-transformed infrared spectrometer (FTIR) and x-ray photoelectron spectroscopy (XPS). The results show that a-C:F films are mainly composed of CF radical at lower powers but of CF2 radical at higher powers. The deposition of films is related to the radicals generated in plasma and the main bonding configurations are dependent on the ratio of CF to CF2 radicals in films.

Simulation of nonlinear behavior in an electron cyclotron resonance plasma

Some nonlinear behavior in electron cyclotron resonance plasma was investigated using a two-dimension hybrid-mode with self-consistent microwave absorption. The saturation,oscillations of plasma parameters (plasma density, potential, electron temperature) versus operating conditions (pressure, power) are discussed. Our simulation results are consistent qualitatively with many experimental measurements.

Correlation ofⅢ/Ⅴsemiconductor etch results with physical parameters of high-density reactive plasmas excited by electron cyclotron resonance

Reactive ion etching is the interaction of reactive plasmas with surfaces. To obtain a detailed understanding of this process, significant properties of reactive composite low-pressure plasmas driven by electron cyclotron resonance（ECR） were investigated and compared with the radial uniformity of the etch rate. The determination of the electronic properties of chlorine-and hydrogen-containing plasmas enabled the understanding of the pressure-dependent behavior of the plasma density and provided better insights into the electronic parameters of reactive etch gases. From the electrical evaluation of I（V） characteristics obtained using a Langmuir probe,plasmas of different compositions were investigated. The standard method of Druyvesteyn to derive the electron energy distribution functions by the second derivative of the I（V）characteristics was replaced by a mathematical model which has been evolved to be more robust against noise, mainly, because the first derivative of the I（V） characteristics is used. Special attention was given to the power of the energy dependence in the exponent. In particular, for plasmas that are generated by ECR with EM modes, the existence of Maxwellian distribution functions is not to be taken as a self-evident fact, but the bi-Maxwellian distribution was proven for Ar-and Kr-stabilized plasmas. In addition to the electron temperature, the global uniform discharge model has been shown to be useful for calculating the neutral gas temperature. To what extent the invasive method of using a Langmuir probe could be replaced with the noninvasive optical method of emission spectroscopy, particularly actinometry, was investigated,and the resulting data exhibited the same relative behavior as the Langmuir data. The correlation with etchrate data reveals the large chemical part of the removal process—most striking when the data is compared with etching in pure argon. Although the relative amount of the radial variation of plasma density and etch rate is approximately ？5%, the etch rate shows a slightly concave shape in contrast to the plasma density.

Measurement of the Electron Bernstein Wave Emission with One of the Power Transmission Lines for ECH in LHD

Possibility of the measurement of radiated waves derived from the thermally emitted electron Bernstein wave （EBW） is numerically investigated based on the assumption of the super dense core （SDC） plasma generated in LHD. EBW that is thermally emitted in the electron cyclotron resonance （ECR） layer may couple with the electromagnetic wave and be emitted to the vacuum via the EBW-extraordinary-ordinary （B-X-O） mode conversion process. We consider the use of one of the transmission lines for electron cyclotron heating （ECH） in LHD as a receiving system of the emission. It is derived that the waves in the fundamental cyclotron frequency range are emitted as the EBW near their upper hybrid resonance （UHR） layer outside the last close flux surface （LCFS）. On the other hand, waves in the second harmonics cyclotron frequency range are emitted in the core region. It means that successful measurement of waves of the second harmonic frequency range emitted from extremely high dense core plasma with setting an aim angle for receiving indicates a possibility of the second harmonic ECH by EBW in the core region with setting the same aim angle and the same polarization for launching.

Investigation of Experimental Con6guration for Electron Bernstein Wave Heating on LHD

Investigation of experimental configuration for the electron Bernstein wave （EBW） heating by using the existing electron cyclotron heating （ECH） antennas on LHD was performed. By using an antenna installed in the lower port, direct oblique launching of the extraordinary （X-） mode from the high magnetic field side （HFS） is available. Since the parallel component of the refractive index （NIF） varies during propagation because of the inhomogeneity of the magnetic field, NH can be zero when the launched X-mode crosses the fundamental electron cyclotron resonance （ECR） layer even NⅡ is noonzero initially. In such a condition, if the electron density is above a certain level the obliquely launched X-mode can pass the fundamental ECR layer without being damped out and can be mode-converted to EBW that is absorbed at the Doppler shifted ECR layer. By using an antenna installed in the horizontal port, oblique launching from the lower magnetic field side （LFS） toward the over-dense plasma is available. Excitation of EBW via the mode conversion process of ordinary mode（O）-extraordinary mode（X）-electron Bernstein wave （B） is expected with the O-mode launching toward an appropriate direction. The O-X-B mode conversion rate and the region of power deposition were surveyed by varying the magnetic field strength and the launching direction. The results of the survey suggest that efficient heating in the core region is difficult by using the existing antenna. Rearrangement of the final mirror of the launching antenna may be needed.

自研28 GHz/50 kW回旋管实现长时间连续运行

介绍了中国工程物理研究院应用电子学研究所针对磁约束聚变装置电子回旋共振加热(ECRH)系统、重离子加速器电子回旋共振(ECR)离子源以及前沿科技探索应用研制的28 GHz/50 kW连续波回旋管最新实验结果。研究团队在2019年该回旋管实现50 kW/30 s运行的基础上,通过结构优化和稳定性设计验证,最终实现了在10~50 kW功率范围多个功率水平的稳定长时间连续运行,典型运行结果为16 kW/3000 s、26 kW/900 s、46 kW/1800 s、50 kW/300 s,特别在输出功率32 kW连续稳定工作了400 min。这是国内首次研制出小时级连续工作的中等功率回旋管。

微波等离子体制备类金刚石薄膜进展

随着对材料需求的日渐增长,在材料表面沉积性能优异的薄膜以提高材料的使用性能成为一种趋势。类金刚石薄膜具有高硬度、强的耐腐蚀性能、低摩擦因数、良好的耐磨损性等优势,在工业制造领域受到越来越多的关注。介绍了电子回旋共振等离子体源和表面波等离子体源的原理及在制备DLC薄膜中的应用,分析了沉积过程中影响DLC薄膜性能的主要因素,指出了目前存在的问题,总结了微波等离子体源能够产生大面积的高密度等离子体,且无电极污染等优势,为促进高性能DLC薄膜的制备和应用提供参考。

Practical 2.45-GHz microwave-driven Cs-free Hˉ ion source developed at Peking University

A practical 2.45-GHz microwave-driven Cs-free H^- source was improved based on the experimental H^- source at Peking University（PKU）. Several structural improvements were implemented to meet the practical requirements of Xi＇an Proton Application Facility（XiPaf）. Firstly, the plasma chamber size was optimized to enhance the plasma intensity and stability. Secondly, the filter magnetic field and electron deflecting magnetic field were enhanced to reduce co-extracted electrons. Thirdly, a new two-electrode extraction system with farther electrode gap and enhanced water cooling ability to diminish spark and sputter during beam extraction was applied. At last, the direct H^- current measuring method was adopted by the arrangement of a new pair of bending magnets before Faraday cup（FC） to remove residual electrons. With these improvements, electron cyclotron resonance（ECR） magnetic field optimization experiments and operation parameter variation experiments were carried out on the H^- ion source and a maximum 8.5-mA pure H^- beam was extracted at 50 kV with the time structure of 100 Hz/0.3 ms. The root-mean-square（RMS） emittance of the beam is 0.25 Π·mm·mrad. This improved H^- source and extraction system were maintenance-free for more than 200 hours in operation.

Interaction between plasma and electromagnetic field in ion source of 10 cm ECR ion thruster

Through diagnosing the plasma density and calculating the intensity of microwave electric field,four 10 cm electron cyclotron resonance(ECR)ion sources with different magnetic field structures are studied to reveal the inside interaction between the plasma,magnetic field and microwave electric field.From the diagnosing result it can be found that the plasma density distribution is controlled by the plasma generation and electron loss volumes associated with the magnetic field and microwave power level.Based on the cold plasma hypothesis and diagnosing result,the microwave electric field intensity distribution in the plasma is calculated.The result shows that the plasma will significantly change the distribution of the microwave electric field intensity to form a bow shape.From the boundary region of the shape to the center,the electric field intensity varies from higher to lower and the diagnosed density inversely changes.If the bow and its inside lower electric field intensity region are close to the screen grid,the performance of ion beam extracting will be better.The study can provide useful information for the creating of 10 cm ECR ion source and understanding its mechanism.

Understanding hydrogen plasma processes based on the diagnostic results of 2.45 GHz ECRIS at Peking University

Optical emission spectroscopy（OES）, as a simple in situ method without disturbing the plasma, has been performed for the plasma diagnosis of a 2.45 GHz permanent magnet electron cyclotron resonance（PMECR） ion source at Peking University（PKU）. A spectrum measurement platform has been set up with the quartz-chamber electron cyclotron resonance（ECR） ion source [Patent Number： ZL 201110026605.4] and experiments were carried out recently. The electron temperature and electron density inside the ECR plasma chamber have been measured with the method of line intensity ratio of noble gas. Hydrogen plasma processes inside the discharge chamber are discussed based on the diagnostic results. What is more, the superiority of the method of line intensity ratio of noble gas is indicated with a comparison to line intensity ratio of hydrogen. Details will be presented in this paper.

Development of plasma sources for Dipole Research EXperiment(DREX)

Dipole Research EXperiment（DREX） is a new terrella device as part of the Space Plasma Environment Research Facility（SPERF） for laboratory studies of space physics relevant to the inner magnetospheric plasmas. Adequate plasma sources are very important for DREX to achieve its scientific goals. According to different research requirements, there are two density regimes for DREX. The low density regime will be achieved by an electron cyclotron resonance（ECR） system for the ‘whistler/chorus＇ wave investigation, while the high density regime will be achieved by biased cold cathode discharge for the desired ‘Alfvén＇ wave study. The parameters of ‘whistler/chorus＇ waves and ‘Alfvén＇ waves are determined by the scaling law between space and laboratory plasmas in the current device. In this paper, the initial design of these two plasma sources for DREX is described. Focus is placed on the chosen frequency and operation mode of the ECR system which will produce relatively low density ‘artificial radiation belt＇ plasmas and the seed electrons, followed by the design of biased cold cathode discharge to generate plasma with high density.

应用于电推进的碘工质电子回旋共振等离子体源

电子回旋共振(electron cyclotron resonance,ECR)源具有无需内电极、低气压电离、等离子体密度较高和结构紧凑等优点,适用于小功率电推进.因此,研究小功率碘工质ECR等离子体源具有重要意义.本文首先设计了一套耐腐蚀且可以均衡稳定输出碘蒸汽的储供系统;然后完成了耐碘腐蚀ECR推力器设计,利用耐腐蚀的同轴谐振腔结构将微波馈送到推力器,并将通道磁场变为会切型磁场以产生更多ECR层;最终联合点火实验成功,成为国际上首个可以用于电推进的ECR电离碘工质等离子体源.分析实验和静磁场、微波电场分布发现,小功率、低流量下的不稳定等离子体羽流闪烁由寻常波电子等离子体共振加热和非寻常波ECR加热模式之间的转化引起.高流量下电离率下降是由电子损失、壁面损失和碘工质电负性导致.并依据此原理提出了改进方案.放电后等离子体源没有明显损伤,说明具备长寿命潜力.此项工作初步证实了小功率碘工质ECR电推进方案可行.

放电室长度对电子回旋共振离子推力器性能的影响机理

在电子回旋共振离子推力器的结构优化中,放电室长度调节的是栅极与主等离子体区的相对位置,以此影响栅极上游等离子体密度,进而改变推力器离子束流大小及聚焦状态,达到性能优化目的.然而,在一体化仿真研究中发现,施加栅极电压后,Child-Langmuir鞘层前存在高能电子分布,这与传统的放电室仿真存在明显差异.本文认为施加栅极电压后,Child-Langmuir鞘层会排斥电子,使流向栅极的电子返回磁镜区参与加热,最终在磁镜和Child-Langmuir鞘层之间形成了高能电子分布区域.这意味着放电室长度对推力器性能的影响不再局限于相对位置的调节,还能通过调控Child-Langmuir鞘层前的高能电子分布影响等离子体生成.因此,本文采用一体化仿真方法,系统研究了放电室长度对推力器放电和引出性能的影响机理,并讨论了Child-Langmuir鞘层前高能电子分布对电离体系的影响.本文研究将为电子回旋共振离子推力器的结构优化设计提供新思路.

双放电腔微波-ECR等离子体源增强磁控溅射沉积技术

因其设备简单、沉积速率高等特点 ,磁控溅射沉积技术被广泛地用于各种薄膜制备中 .但用反应磁控溅射制备化合物薄膜如氧化物、氮化物膜时 ,为了得到化学配比的膜层 ,薄膜生长表面的反应激活基团、离子等的密度必须足够大 .为此对原有的微波 -ECR等离子体源进行了改造 .研究了双放电腔微波 -ECR等离子体源增强磁控溅射的放电特性 ,并用该方法制备了氮化碳膜 .结果表明 :该方法是一种有效的制备化合物薄膜的技术 ;用该方法制备的氮化碳膜 。

Langmuir探针诊断微波ECR非平衡磁控溅射等离子体

利用朗谬尔探针诊断了ECR非平衡磁控溅射等离子体,给出了微观等离子体参量随宏观工艺参量变化关系。实验测得基片架附近等离子体密度达到1010～1011数量级,电子温度在(5～10)eV之间。随溅射靶功率变化,等离子体密度在130W时取得最大值;同样随微波源功率变化,等离子体密度在功率为850W时也达到最大值。电子温度、等离子体空间电位变化与等离子体密度呈相同趋势。

HL-2A装置2MW电子回旋共振加热系统研制

HL-2A装置电子回旋共振加热系统的主要指标是2MW/1s/68GHz,系统由4个单元组成,每个单元包括一只回旋管,微波传输系统,控制保护测量和冷却等子系统。通过对ECRH系统和回旋管的调试,每只管子微波输出功率500kW,脉冲宽度1s,四管并联运行时总输出功率达到1.63MW,系统使用效率高于80%。

微型电子回旋共振离子推力器离子源结构优化实验研究

微型电子回旋共振(ECR)离子推力器可满足微小航天器空间探测的推进需求.为此,本文开展直径20mm的微型ECR离子源结构优化实验研究.根据放电室内静磁场和ECR谐振区的分布特点,研究不同微波耦合输入位置对离子源性能的影响,结果表明环形天线处在高于ECR谐振强度的强磁场区域时,微波与等离子体实现无损耦合,电子共振加热效果显著,引出离子束流较大.根据放电室电磁截止特性,结合微波电场计算,研究放电容积对离子源性能的影响,实验表明过长或过短的腔体长度会导致引出离子束流下降甚至等离子体熄灭.经优化后离子源性能测试表明,在入射微波功率2.1 W、氩气流量14.9μg/s下,可引出离子束流5.4 mA,气体放电损耗和利用率分别为389 W/A和15%.

用于半导体加工的腔耦合－磁多极型ECR源的研究

本实验室研制出一台谐振腔耦合一多极场位形的电子回旋共振（ＥＣＲ）微波等离子体源（ＭＥＰ）。采用朗谬探针和离子能量分析器，测量了ＭＥＰ中Ａｒ等离子体的放电特性。实验结果表明．ＭＥＰ能在很宽的运行参数范围，高效率地产生具有较高密度、较低离子温度和空间电位的大面积均匀等离子体，特别适合于半导体加工应用研究。

等离子体辅助原子层沉积氧化铝薄膜的研究

为在室温条件下进行氧化铝薄膜的原子层沉积,自行设计了一套微波回旋共振等离子体辅助原子层沉积装置,以三甲基铝作为铝源前躯体,氧气作为氧化剂,在室温下于氢氟酸溶液中处理过的单晶硅基片上进行了氧化铝薄膜的沉积。利用扫描电子显微镜、原子力显微镜、高分辨率透射电子显微镜、X-ray射线衍射、X-ray射线光电子能谱等分析手段测试了薄膜的表面形貌和成分,结果表明制备的氧化铝薄膜为非晶态结构,铝、氧元素含量配比接近2/3,同时薄膜表面非常光滑平整而且致密,表面粗糙度<0.4nm。通过高分辨率透射电子显微镜的截面图,可以估算出薄膜厚度约为80nm,界面非常清晰、平整,薄膜质量较高,沉积速率为0.27nm/周期,沉积速率较热沉积大大提高。