低压双液体变焦透镜的理论及工艺研究

通过对仅有单层介电薄膜双液体变焦透镜模型的相关理论分析,得出介电层薄膜的厚度及均匀性对双液体变焦透镜的性能影响很大,并绘制了双液体变焦透镜焦距与驱动电压、介电层厚度的关系曲线.在此基础上,以降低双液体变焦透镜的驱动电压为目的,对介电层的选择进行了分析,选择既可充当介电层又可充当疏水层的派瑞林材料作为双液体变焦透镜的介电层材料,通过真空蒸发镀膜工艺得到了合适厚度的介电层派瑞林薄膜,并对所镀薄膜表面形貌以及厚度进行了测试.选择氯化钾以及溴代十二烷作为导电液体和油性液体,利用离心方式除去液体中溶有的气体,进而制作完成双液体变焦透镜样品.电驱变焦实验得到低压双液体变焦透镜样品的变焦范围为±20mm,驱动电压约为30V,对于实验过程中出现的迟滞效应,通过对杨氏方程中引入摩擦力项,合理地解释了其原因.     

双层介电薄膜结构双液体变焦透镜的研究

在双层介电薄膜结构双液体变焦透镜模型的基础上,分析了透镜焦距与外加电压、双层介电薄膜的介电常量、薄膜厚度等参量的关系.并以降低双液体变焦透镜驱动电压为目的,选择了相对介电常量较高的五氧化二钽薄膜作为内层介电层,相对介电常量较低的防水层为外层介电层,分析了双层介电薄膜的厚度以及厚度的匹配对双液体变焦透镜的变焦范围和驱动电压的影响,在保证一定的变焦范围并尽可能降低透镜驱动电压情况下获得最佳透镜工艺参量.模拟结果表明:疏水层薄膜厚度比高介电层薄膜厚度小很多时,双液体变焦透镜可实现低压驱动,且双液体变焦透镜在一定变焦范围内所需驱动电压可下降到10V以下,而疏水层薄膜厚度与高介电层薄膜厚度相当或高于高介电层薄膜厚度都不能有效利用高介电薄膜的高介电性能来降低双液体变焦透镜的驱动电压.     

高频H型放电离子源的场特性

 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。     

基于电湿效应的双液体透镜

介绍了一种新型的、基于电湿效应的双液体透镜的发展历史、结构原理,通过改变外加电压的大小以调节透镜的焦距,从而达到无机械运动变焦的目的.推导并分析了两种液体透镜模型的焦距与外加电压的关系.     

介电弹性体驱动液体透镜的设计与分析

介电弹性体具有结构紧凑、形变量大、响应速度快及易集成等特点,为了降低驱动电压,将介电弹性体应用于液体透镜中,采用介电弹性体和透镜薄膜分离结构,建立了介电弹性体主动薄膜变形、透镜薄膜变形以及液体透镜焦距的数学模型。仿真结果表明,当初始液体压力为500 Pa、驱动电压为1000 V时,液体透镜的变焦范围为15.13～22.80 mm,焦距增加了为51%。分析了介电弹性体的杨氏模量、残余应力、初始厚度及半径对液体透镜焦距的影响,结果表明,同等增加倍率下,介电弹性体的初始厚度对液体透镜焦距的影响最大,其次为残余应力,该研究结果可为优化设计介电弹性体驱动的液体透镜提供参考。     

高频离子源参数研究

从自由电子在高频电场中的运动方程出发，研究了高频离子源的工作原理。由边界条件和电离条件推导出截止条件和最低点火电压的关系式。在此基础上编出了适于在各种气压下计算各种气体的Ｕｂ－ｆ曲线程序，作出了大量的计算结果。由计算结果讨论了高频离子源工作时各种参数之间的制约关系。所得结果将为利用高频离子源产生Ｈ＋ｎ离子团簇的实验提供重要的依据。     

示波管中静电透镜成像性质的研究

在电磁场仿真计算的辅助下,为8SJ45J型示波管中单透镜的电势分布建立了简化模型,利用该模型可以得到单透镜的简正焦距随聚焦/加速电压比的变化关系,并在已有的仿真计算数据基础上拟合出焦距经验公式.运用这一经验公式并结合简正主点的性质证明了单透镜存在两种使电子束聚焦的电压比,在这两种电压比下聚焦系统形成的静电透镜完全等效.     

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为提高NBI系统的稳定运行参数和可靠性,研制了一台基于高频开关电源技术的全固态调制输出负高压测试电源,并将HL-2A装置NBI系统原4套抑制极电源的电子管调制器改为基于IGBT串联技术的全固态调制器.对比原抑制极电源系统,给出了基于高频开关技术和IGBT串联技术的抑制极电源结构.结合NBI系统调试实验,通过调节抑制极电源电压,瞬态电流输出能力,分析了抑制极电源输出性能对离子源束流引出特性,离子源引出电极击穿特性的影响,获得了引出稳定离子束流的最低抑制电压.     

用于NPA标定系统的高频离子源研制

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.     

基于氧负离子PIG源的原子氧产生装置

近地轨道能量为5eV的原子氧对航天器表面影响的地面等效模拟,是世界各航天国家竟相研究的重要领域.本文介绍一种基于氧负离子PIG源的原子氧产生装置,本装置由永磁PIG离子源、两电极引出系统、电子过滤器、单透镜、减速电极和样品架组成.目前,这一装置已安装在中国科学院空间科学与应用研究中心小碎片加速器上,并开展了初步实验.当离子源放电电流50mA,在2kV和3kV的引出电压下,引出的氧负离子分别为200μA和3001μA.并开展了减速实验和kapton膜的溅蚀研究.由于原子氧装置和小碎片加速器供用同一个靶室.因此,这一安排还可以同时开展小碎片和原子氧对空间材料的撞击和侵蚀的研究.     

NSCL/MSU ECR离子源项目进展报告

Since the last ECR Workshop,NSCL/MSU has been involved in a vigorous ECR ion source R&D program,which resulted in the construction of an off-line test ECR ion source(ARTEMIS-B)for new beam development and ion optics studies.Also the design and partial completion of a 3rd generation,fully superconducting ECR ion source,SuSI has been accomplished.This paper is an overview of the construction projects and the different R&D activities performed with the existing ion sources.These activities include development of metallic ion beam production methods using evaporation with resistive and inductive ovens and sputtering of very refractory metals.Ion optics developments include testing different focusing elements(magnetic solenoid lens,electrostatic quadrupole triplet lens,Einzel lens,electrostatic double doublet quadrupole combined with an octupole lens),and different beam forming and diagnostics devices.The detailed results will be presented at the workshop in separate talks and posters.     

Novel matching lens and spherical ionizer for a cesium sputter ion source

The beam optics of a multi-sample sputter ion source, based on the NEC MCSNICS, has been modified to accommodate cathode voltages higher than 5 kV and dispenses with the nominal extractor. The cathode voltage in Cs sputter sources plays the role of the classical extractor accomplishing the acceleration of beam particles from eV to keV energy, minimizing space charge effects and interactions between the beam and residual gas. The higher the cathode voltage, the smaller are these contributions to the emittance growth. The higher cathode voltage also raises the Child’s law limit on the Cs current resulting in substantially increased output. The incidental focusing role of the extractor is reallocated to a deceleration Einzel lens and the velocity change needed to match to the pre-acceleration tube goes to a new electrode at the tube entrance. All electrodes are large enough to ensure that the beam fills less than 30% of the aperture to minimize aberrations. The improvements are applicable to sputter sources generally.     

Study on the Relation Between Discharge Voltage and Magnetic Field Topography in a Hall Thruster Discharge Channel

The relation between magnetic field topography and operating voltage is investigated in a 1kW Hall thruster discharge channel in order to focus the ion beam effectively and optimize the performance. The curvature of magnetic field line (α) is introduced to characterize the differences of topologies. The optimized magnetic field distribution under each operating voltage is obtained by experiment. Through the curvature transformation, we find that the area of (α > 1) in the channel gradually decreases with the increase of the operating voltage. In response to the results above, two dimensional plasma flows are simulated employing Particle‐in‐Cell method. The distributions of the electric potential, ion density and ion radial velocity are calculated to understand the important influence of the relation above on ion beam focusing. The numerical results indicate that magnetic field curvature and thermal electric field control the ion beam in the ionization and acceleration zone, respectively. The magnetic field topography and discharge voltage interact with each other and together form the focusing electric field. The ion radial mobility is suppressed effectively and the ion beam is focused to the channel centerline. In addition, for a given voltages, when the area of (α > 1) is larger than the optimal scope, the electric potential lines excessively bend to the anode causing ion over focus; contrarily, the electric potential lines will bend to the exit and defocus ions. All these results suggest the relation between magnetic field topography and discharge voltage is important to the ion radial flow control and performance optimization of the Hall thruster (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

用于静电加速器的高频离子源及其引出特性

 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。     

HL-2M装置中性束注入加热系统研制进展

为开展磁约束堆芯燃烧等离子体物理实验,正在建造的HL-2M装置拟建造3条5 MW的中性束注入加热束线。简要概述了HL-2M装置NBI加热系统的总体规划,第1条5MW-NBI加热束线的设计,离子源调试实验,注入器核心部件的安装和测试结果。通过调试,目前单个离子源引出束流达到36 A,加速电压75 kV,离子束功率达到2.4 MW,脉冲宽度3 s。通过测试发现:注入器的4条离子束汇聚角误差小于±0.1°,残留离子偏转磁体的磁场测试值与模拟计算值偏差小于±5%,注入器静态真空值达到1.0×10-3 Pa。注入器采用大型非标低温泵,低温泵的抽速达到2.40×106 L/s。第1条5MW-NBI加热束线的试装和测试结果表明,该束线能够满足HL-2M装置NBI加热的技术要求。     

RF离子源引出特性的研究

 为了使RF离子源具有良好的引出特性，测试了吸极几何参数、振荡器板压和引出电压对离子源聚焦度的影响，对实验结果进行了分析。在其它参数不变的情况下，吸极的外径D与内径d之比存在最佳值，增加D/d，有利于过聚焦的离子束恢复聚焦状态。吸极的长度为L，石英套管比吸极长l。当l/D增大时，聚焦度上升，引出束流下降。L/d之比减小时，聚焦度增大。当L/d小于4时，聚焦度增加趋势变缓。综合考虑聚焦度、引出束流和气压，D/d，l/D，L/d适宜的选择范围分别为1.6～2.1，0.7～1.1,4～7。增加振荡器功率会使离子束呈弱聚焦，而增加引出电压会使离子束呈过聚焦。振荡器功率和引出电压都存在最佳值。     

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为EAST装置中性束注入器设计了一套用于将剩余离子在线电偏转的结构,并对系统各设备的核心参数进行了估算。在4.41kV偏转电压作用下,该电偏转系统可提供80keV氘离子束偏转所需的偏转电场。在偏转电场调制情况下,该电偏转系统可有效降低极板表面的热负荷,进而满足EAST中性束注入器稳态运行的需要。     

中性束注入器电偏转系统的参数设计与估算研究

为EAST 装置中性束注入器设计了一套用于将剩余离子在线电偏转的结构,并对系统各设备的核心参数进行了估算。在4.41kV 偏转电压作用下,该电偏转系统可提供80keV 氘离子束偏转所需的偏转电场。在偏转电场调制情况下,该电偏转系统可有效降低极板表面的热负荷,进而满足EAST 中性束注入器稳态运行的需要。     

Submicron focusing of XUV radiation from a laser plasma source using a multilayer Laue lens

The focusing properties of a one-dimensional multilayer Laue lens (MLL) were investigated using monochromatic soft X-ray radiation from a table-top, laser-produced plasma source. The MLL was fabricated by a focused ion beam (FIB) structuring of pulsed laser deposited ZrO₂/Ti multilayers. This novel method offers the potential to overcome limitations encountered in electron lithographic processes. Utilizing this multilayer Laue lens, a line focus of XUV radiation from a laser-induced plasma in a nitrogen gas puff target could be generated. The evaluated focal length is close to the designed value of 220 μm for the measurement wavelength of 2.88 nm. Divergence angle and beam waist diameter are measured by a moving knife edge and a far-field experiment, determining all relevant second-order moments based beam parameters. The waist diameter has been found to be approximately 370 nm (FWHM).     

Scattering of a Gaussian Beam by Stepped Index Luneberg Lens

The scattering and focusing characteristics of a Gaussian beam with phase distribution is studied by a stepped index Luneberg lens. A model experiment was performed using a six-layer spherical lens. Two kinds of beams, that is, broad and narrow beam are examined for the incident Gaussian beam. We find that focusing effect of a narrow beam is wholly lower than that of a broad beam. The focal point is also shifted toward outer of sphere because of phase lag for the beam source. The spot size equals almost the wavelength for the various beam parameters.