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1.
高频H型放电离子源的场特性   总被引:1,自引:0,他引:1       下载免费PDF全文
 从Maxwell方程组出发,推导了高频H型放电离子源放电空间的场分布, 并采用Mafia软件进行了三维实体建模,计算了高频离子源放电击穿前和稳定工作后的电磁场分布,得到了高频离子源放电空间电磁场分布的直观图像。通过比较击穿前高频电场的轴向和环向分量,得出了轴向电场在高频离子源击穿中起主要作用的结论,并进而推导出了高频离子源的击穿判据,得出了气体击穿时离子源击穿电压和放电管内气压的关系,与实验结果符合较好。  相似文献   

2.
高频离子源等离子体的光谱诊断   总被引:10,自引:3,他引:7       下载免费PDF全文
 采用发射光谱法研究了高频离子源的等离子体性质。该离子源应用于ZF-200keV中子发生器中,是一种电感耦合型无极环形放电高频离子源。实验采用绝对定标后的光学多道分析系统测定了离子源等离子体在不同阶段氢原子巴耳末谱线系中前三条谱线的强度,并采用部分局部热力学平衡状态的理论,计算出了相应阶段高频离子源等离子体的电子温度、氢原子浓度、氢离子浓度等参数,并进行了简要分析。  相似文献   

3.
为探究射频离子源驱动器线圈电气参数对射频放电的影响,主要进行了射频离子源等离子体激发的物理分析,并计算了射频电源的频率选择与线圈放电电流、线圈匝间电压以及放电气压之间的关系,设计了射频离子源驱动器的主要参数。研制的射频离子源驱动器装置,成功获得氢等离子体射频放电。实验结果和理论计算结果符合很好。  相似文献   

4.
 为了给小型医用回旋加速器提供负氢离子,研制了一台Penning型负氢离子源。采用发射光谱法对该负氢离子源进行了诊断,同时结合离子源功率变化对离子源工作状态进行了分析。实验测量了不同氢气流量、离子源弧流及磁场条件下,该离子源等离子体氢原子巴尔末系中前三条谱线的相对光强和离子源功率变化,分析了不同工作条件对离子源工作状态的影响。结果表明:在可调节范围内,该离子源的工作状态主要受氢气流量的影响,对离子源弧流及磁场的变化不敏感。  相似文献   

5.
用于静电加速器的高频离子源及其引出特性   总被引:2,自引:2,他引:0       下载免费PDF全文
 根据离子束生物工程的需要,设计和研制了一台用于静电加速器的小型高频离子源。针对使用环境从理论上确定了离子源的结构和尺寸。通过实验调试取得了引出束流与引出电压、聚焦电压以及放电气压之间的变化特性曲线,测定了引出束流的束径包络,对束流的不稳定性进行了分析,在设计中采取了有效的措施抑制束流不稳定性。结果表明,离子源的最佳工作条件为引出电压1 600V~1 800V,放电气压在(4~8)×10-4Pa范围,此时离子源可引出最大束流30μA。束流大小及其稳定性均达到预期要求。  相似文献   

6.
为探究射频离子源驱动器线圈电气参数对射频放电的影响,主要进行了射频离子源等离子体激发的物理分析,并计算了射频电源的频率选择与线圈放电电流、线圈匝间电压以及放电气压之间的关系,设计了射频离子源驱动器的主要参数。研制的射频离子源驱动器装置,成功获得氢等离子体射频放电。实验结果和理论计算结果符合很好。  相似文献   

7.
ECR离子源中的微波功率在线测量   总被引:1,自引:1,他引:0       下载免费PDF全文
 在中子发生器中采用ECR离子源是一种新技术。由于受结构的限制,ECR离子源不能像高频源离子源那样通过观察气体放电的颜色判断其工作状态,所以在运行中调节状态非常困难。解决这个问题的方法是:用定向耦合器加微波小功率计的方法在线测量ECR离子源的微波入射功率,通过微波入射功率可以直接得到ECR离子源引出离子束流的大小,从而推断微波信号源的放电过程是否正常,然后调整ECR离子源,最终使中子发生器工作在最佳状态。从ECR离子源后面的引出电极测得的最大束流为20 mA,且工作长时间稳定,当微波功率在160 W~500 W之间时,放电效果较好,离子束流随微波功率的增加而增加。  相似文献   

8.
研制了一台用于Neutral Particle Analyzer(NPA)标定系统的高频离子源,对其性能参数进行了实验测量,得到引出束流与高频振荡器板压、引出电压及放电气压之间的特性曲线,对影响引出束流稳定性的原因进行了分析.结果表明:当工作气体为氢气,在板压580 V、引出电压1600 V、聚焦电压1550 V和气压9.5×10~(-4) Pa时,能引出66μA的离子流;在41μA束流条件下,4小时内的束流稳定性优于2.6%,影响束流稳定性的主要因素是放电管内工作气体气压的波动和等离子体温度的升高.此结果可以满足HL-2A/M上NPA系统的标定对离子源的要求.  相似文献   

9.
基于p-n结二极管的理想工作状态的基本假定,推导了二极管在交流电下工作时其基区和p-n结分界面附近上的时间常数与二极管空间尺寸、扩散长度、载流子寿命和外加交流电频率等的依赖关系.结果发现高频和低频两种状态下二极管各类特征参量对时间常数的作用不一样.低频条件下,二极管的时间常数由材料本身来决定,与外加电流频率无关.高频情况下,时间常数则与半导体材料性质无关,只由外加交流电的频率来决定.  相似文献   

10.
报道了H+5的实验结果.分析讨论了H+5的形成和分解途径.根据理论分析,以稳定的H+3为核心与一个或多个氢分子结合可能形成稳定的H+n氢团簇离子.另一方面,在高频离子源中, 有发生H+3与H2反应的条件.实验中,从高频离子源引出的离子束被静电加速器加速,然后用90°磁分析器选择质量数为5的离子,再将这些离子偏转20°,最后在20°方向测量它们的能谱.从能谱发现,在高频离子源中可能通过H+3与H2的离子-分子反应形成了H+5团簇离子;并且在H+5的分解产物中还发现可能存在H3和H4等中性团簇产物.  相似文献   

11.
In this paper, the wave transmission from finite photonic crystals with multiple alternations is investigated using boundary element method (BEM). Since that, in these structures the alternation is not in all directions of space; the investigations of the frequency band gap with desired accuracy are not practical by analytical methods. Also, the frequency dispersion of dielectric rods is an effective parameter in photonic crystals, which this effect in our calculations has been considered. Due to the high capabilities of the BEM, the transmitted wave spectrum in the photonic crystal is calculated by changing the geometrical and optical parameters of the photonic crystal and applying more alternation in its structure and the position and width of the frequency band gap is investigated. Then, it is assumed that the photonic crystal with an arbitrary angle is rotated around the axis which is perpendicular on the crystal cross section and then, it is irradiated with a plan wave. The band gap of the photonic crystals with the desired structure, desired rotation angle and multiple alternations have been solved. Very low information volume, high speed and accuracy during the calculation and useable for any desired structures are the characteristics of this method.  相似文献   

12.
等离子体中非线性朗谬尔波的哈密顿描述   总被引:1,自引:1,他引:0  
研究了在双离子(H^ ,O^ )成份等离子体中的非线性朗谬尔波的特性,从流体方程出发,考虑低频离子运动的完全非线性和双极势的色散,得到了描述高频电场缓变振幅与低频势扰动的耦合方程组。利用哈密顿方法,在小振幅情况下,对方程组解耦合,利用Sagdeev势方法,对孤立波的性状进行了讨论,结果表明,双离子成份等离子体中双极势的孤立子的幅度相对电子,离子等离子体的双极势孤立子的幅度要大,而相应的高频电场强度的幅度相对要小,相应的孤立子的速度传播区也较小。  相似文献   

13.
Confined dual frequency hydrogen plasma discharge has been investigated with microwave interferometer method and radial profiles are taken by Abel inversion technique. Dual radio-frequency sources, operating at 27.12MHz and 1.94MHz, are coupled to each other through the plasma. 27.12MHz RF power is used to enhance plasma density and 1.94MHz power is used to enhance ion acceleration energy to the electrode. Radial density profiles has been taken for comparing the effects of low frequency source that the secondary RF source causes reduction in plasma density due to the sheath expansion. Instead radial density profile is assumed as flat by most of the models, there is about 2.5eV of potential drop occurs from centre to boundary at 40W of primary source power. It has been observed that increasing sheath width (increasing the secondary source power to primary source power) reduces the bulk plasma volume and makes potential profile flattening in y direction. While the high frequency power is dissipated by electrons in the bulk plasma; low frequency power is mostly dissipated by ions in the sheath region. Using both high and low frequency power, we may control plasma density and ion acceleration energy to the electrode simultaneously.  相似文献   

14.
The bond parameters for the nearest neighbors have been determined along with the ion charges for CdGeP2 on the basis of infrared reflection; the Cd-P and Ge-P bond matrices are similar to those for InP and GaP. The ion charges agree with those calculated from the dielectric theory. The lattice-vibration spectrum has been calculated in the long-wave limit for directions of high symmetry. The nonanalytic behavior of the frequency in the long-wave limit has also been examined. The oscillator strengths have been calculated for the optically active frequencies, and the components of the tensor for the static dielectric constant agree well with experiment.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 109–113, June, 1976.We are indebted to Dr. Bettini for making available his results before publication.  相似文献   

15.
柴路  牛跃  栗岩锋  胡明列  王清月 《物理学报》2016,65(7):70702-070702
太赫兹技术在最近30年来得到快速发展, 并在医学、生物、农业、材料、安检、通信、天文等领域得到广泛应用. 从太赫兹源的频谱特性可以分为窄带(单频)太赫兹源和宽带太赫兹源. 从频谱技术方面来说, 相干的宽带和窄带太赫兹谱是一种互补性关系, 具有各自的技术特点和应用范围. 宽带太赫兹谱可以用于快速获取较宽频谱范围的分子振转谱, 实现混合特征谱的快速检测或成像. 窄带太赫兹源具有很好的光谱灵敏度和分辨率, 适用于太赫兹抽运-探测、分子振转能级谱精细结构分辨 以及太赫兹远程探测和成像. 因此研制具有可调谐的高峰值功率的窄带太赫兹源是适用于探测和识别分子振转能级指纹谱的应用需求, 而差频技术是获得高功率和宽调谐窄带太赫兹源最重要的技术之一. 为了突出该技术的最新进展, 本综述引证论文仅仅限于近5 年来基于差频技术产生太赫兹波的研究进展, 分为光学激光差频源和量子级联激光器差频源两大部分. 对于光学激光差频源, 分别对目前文献报道的各种双波长差频源和太赫兹产生用的非线性晶体进行分类介绍, 并给出所采用的技术和实验结果; 对于量子级联激光器差频源, 分别介绍了量子级联激光器中的差频产生技术和波长调谐技术的最新进展. 量子级联激光器差频太赫兹源是目前实现量子级联激光器在太赫兹波段室温运转的惟一技术, 是实现小型化、窄带宽调谐和室温运转太赫兹源的新发展领域, 值得关注.  相似文献   

16.
射频等离子体鞘层动力学模型   总被引:2,自引:0,他引:2       下载免费PDF全文
戴忠玲  王友年  马腾才 《物理学报》2001,50(12):2398-2402
在流体力学方程的基础上建立了一种自洽的无碰撞射频等离子体鞘层动力学模型.这种自洽性包含两个方面:一方面,由于考虑了瞬时鞘层电场对离子运动的影响,因此该模型适用于描述任意频率段的射频鞘层演化过程;另一方面,在模型中采用等效电路方法来自洽地确定极板上的瞬时电位与瞬时鞘层厚度之间的关系.采用数值方法模拟出鞘层的瞬时厚度及极板的瞬时电位变化、鞘层内离子密度和电场强度等物理量的时空变化.结果表明,当射频场的频率小于或等于离子等离子体频率时,离子流密度明显地随时间变化 关键词: 射频 离子 鞘层 流体力学  相似文献   

17.
A high efficiency launcher of quasi-optical (QO) mode converters for high power gyrotrons have been designed and tested. A helical cut launcher radiates the RF power via its straight cut onto the first phase correcting mirror. The launchers have been optimized for the TE31.8 mode at 170 GHz and TE22.6 mode at 110 GHz by numerically optimizing a launcher surface. The helical cut of the launcher has been optimized by taking the taper angle into account. Further more, the amplitude of the surface perturbation have been optimized for improved focusing in order to reduce the diffraction losses at the helical cut. Low power measurement shows a good agreement with the design. High efficiency characteristics of the design have also been calculated on the assumption of frequency downshift due to the thermal expansion of the cavity and stepwise frequency tuning by changing the operating mode. Besides, the possibility of high efficiency launcher for higher mode is discussed, and these results give the prospect to high efficiency long pulse gyrotrons.  相似文献   

18.
Optical frequency up-conversion is a technique, based on sum frequency generation in a non-linear optical medium, in which signal light from one frequency (wavelength) is converted to another frequency. By using this technique, near infrared light can be converted to light in the visible or near visible range and therefore detected by commercially available visible detectors with high efficiency and low noise. The National Institute of Standards and Technology (NIST) has adapted the frequency up-conversion technique to develop highly efficient and sensitive single photon detectors and a spectrometer for use at telecommunication wavelengths. The NIST team used these single photon up-conversion detectors and spectrometer in a variety of pioneering research projects including the implementation of a quantum key distribution system; the demonstration of a detector with a temporal resolution beyond the jitter limitation of commercial single photon detectors; the characterization of an entangled photon pair source, including a direct spectrum measurement for photons generated in spontaneous parametric down-conversion; the characterization of single photons from quantum dots including the measurement of carrier lifetime with escalated high accuracy and the demonstration of the converted quantum dot photons preserving their non-classical features; the observation of 2nd, 3rd and 4th order temporal correlations of near infrared single photons from coherent and pseudo-thermal sources following frequency up-conversion; a study on the time-resolving measurement capability of the detectors using a short pulse pump and; evaluating the modulation of a single photon wave packet for better interfacing of independent sources. In this article, we will present an overview of the frequency up-conversion technique, introduce its applications in quantum information systems and discuss its unique features and prospects for the future.  相似文献   

19.
利用约瑟夫森效应获取电磁信号的频谱信息是超导电子学的重要应用之一.我们在实验室已搭建的高频信号频谱检测系统基础上,研究了前置放大器的噪声参数对整个高频信号检测系统性能产生的影响.通过实验,我们将两个不同输入电压噪声密度的低噪声放大器应用于检测系统,并对所得的结果进行了比较.讨论了在前置放大器方面对基于约瑟夫森效应的液氮温区的小型高频信号检测系统进行改进的可能性.  相似文献   

20.
The source frequency has a strong influence on plasma characteristics in RF discharges. Multiple sources at widely different frequencies are often simultaneously used to separately optimize the magnitude and energy of ion fluxes to the substrate. In doing so, the sources are relatively independent of each other. These sources can, however, nonlinearly interact if the frequencies are sufficiently close. The resulting plasma and electrical characteristics can then be significantly different from those due to the sum of the individual sources. In this paper, a plasma equipment model is used to investigate the interaction of multiple frequency sources in capacitively and inductively coupled RF excited plasmas. In capacitively coupled systems, we confirmed that the plasma density increases with increasing frequency but also found that the magnitude of the DC bias and DC sheath voltage decreases. To produce a capacitively coupled discharge having a high plasma density with a large DC bias, we combined low and high frequency sources. The plasma density did increase using the dual frequency system as compared to the single low frequency source. The sources, however, nonlinearly interacted at the grounded wall sheath, thereby shifting both the plasma potential and DC bias. In inductively coupled plasmas (ICP), the frequency of the capacitive substrate bias does not have a significant effect on electron temperature and density. The DC bias and DC sheath voltage at the substrate were, however, found to strongly depend on source frequency. By using additional RF sources at alternate locations in ICP reactors, it was found that the DC bias at the substrate was varied without significantly changing other plasma parameters, such as the substrate sheath potential  相似文献   

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