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本研究是为了设计一套大流量、清洁的真空差分系统.计算了超重反冲核实验装置终端真空差分系统各级的真空度;介绍了差分系统的设计和真空泵、测量设备选择;选择能在高压强下连续运行的新型分子/增压泵作为过渡流范围内的主排气泵,对分子增压泵进行了性能测试并对差分系统进行了模拟靶室实验,最后对实验结果进行了分析. 相似文献
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扫描单模红外光参量振荡(IR-OPO)激光器的波长激发待测分子,并用固定波长的真空紫外(VUV)激光器光电离(PI)探测被红外激发的分子,可获得高灵敏度的中性多原子分子的高分辨红外光谱. 这种方法(IR-VUV-PI)基于真空紫外光电离作为探测,可分辨样品中的不同成分,因此适用于对含同位素,自由基,络合物等通常为非纯的样品进行红外光谱研究. 高分辨的IR-VUV-PI谱可实现对分子单一振转态的选择,在选态的基础上进行真空紫外脉冲场电离零动能光电子谱(VUV-PFI-PE)的研究,可得到高分辨振转解析的光电子谱.被研究的分子包括一卤代甲烷(CH3X(X=Br,I)),乙烯(C2H4),丙炔(C3H4)等. 实验表明,采用高分辨的单模红外光参量振荡器代替先前使用的低分辨红外光参量振荡器可显著的提高IR-VUV-PI和IR-VUV-PFI-PE谱的信噪比. 并进一步讨论了采用IR,VUV,分子束三束同轴以提高IR-VUV-PI和IR-VUV-PFI-PE谱灵敏度的方案. 相似文献
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卫星组网是满足未来空间通信需求的有效方式,为实现空间卫星组网的可视化,设计了一种卫星组网可视化仿真系统;系统由星座设计分系统、星座覆盖性能分析分系统、数据处理分系统和可视化分系统组成;在组网过程中,首先在星座设计分系统中设置星座的参数,根据轨道参数模型计算出星座中每颗卫星的轨道参数,并将计算结果输出给星座覆盖性能分析分系统,完成对纬度、区域和全球覆盖效果的分析、评估和显示;仿真结果表明:系统能够对卫星组网进行实时计算和显示,计算精度比STK仿真软件提高12%,系统运行稳定,界面良好。 相似文献
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为了辐照生物活细胞,束流须经由真空隔离窗引入大气环境中.在真空隔离窗的设计中,对结构、材料种类及其厚度的选择既要尽可能地减小束斑展宽,又要兼顾安全性.应用有限元分析软件对不同结构、不同材料的真空窗进行受力分析,模拟真空窗的形变和等效应力,运用强度理论考察候选真空窗的安全性;并运用SRIM程序模拟离子的小角散射、横向射程,计算入射离子的能量、真空窗材料及其厚度、空气层对束斑展宽的影响;最后提出真空窗适宜的结构、材料及厚度范围. 相似文献
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荧光发射强度在荧光显微术科学观测中至关重要。理论分析了三大影响荧光发射强度的重要因素:分子吸收激发光光子的能力、荧光量子产量及其荧光饱和与荧光猝灭,指出选择具有大光吸收截面和高量子产量的荧光分子,能有效保证荧光发射强度;确定合理的激发光强度范围,可避免不必要的荧光饱和现象。进一步实验研究了超高真空和大气环境下的荧光猝灭现象,得出超高真空时荧光分子的荧光猝灭现象极不明显,而大气环境可造成荧光光强指数递减的结论。 相似文献
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Gerasimos D. Danilatos 《Micron (Oxford, England : 1993)》2012,43(5):600-611
Velocity and ejection pumping are proposed as novel evacuation techniques to assist the static differential pumping already in use in the environmental scanning electron microscope. The gas velocity (or momentum) that accompanies the supersonic jet stream formed through the first pressure limiting aperture is used to initially force the gas out of the system by placing the second pressure limiting aperture at an optimum position in the gaseous jet. By this method, the gaseous particle thickness between the two apertures is minimised and the required pumping speed of the first evacuation stage is also reduced to an absolute minimum. A further improvement is achieved by inserting an appropriately shaped baffle between the two apertures, which shields the second aperture from the gas jet of the first and acts as an ejector-jet pump. The gas leak rate through the second aperture is maintained at an acceptable low level by both systems, even below the static leak rate level when the ejector-jet design is used, in particular. The result of either method has a double benefit, namely, the electron beam loss in the intermediate pumping stage is minimised together with a reduction of pump speed requirements. This translates to best instrument performance and minimal manufacturing costs. 相似文献
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Zook AL Adhyaru BB Bowers CR 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2002,159(2):175-182
A rubidium spin exchange optical pumping system for high capacity production of >65% spin polarized 129Xe gas is described. This system is based on a fiber coupled multiple laser diode array capable of producing an unprecedented 210 W of circularly polarized light at the pumping cell with a laser line width of 1.6 nm. The 129Xe nuclear spin polarization is measured as a function of flow rate, pumping cell pressure, and laser power for varying pumping gas compositions. A maximum 129Xe nuclear polarization of 67% was achieved using a 0.6% Xe mixture at a Xe flow rate of 2.45 sccm. The ability to generate 12% polarized 129Xe at rates in excess of 1L-atm/h is also demonstrated. To achieve production of 129Xe gas at even higher polarization will rely on further optimization of the pumping cell and laser beam geometries in order to mitigate problems associated with temperature gradients that are encountered at high laser power and Rb density. 相似文献
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G.M. Lancaster J.A. Taylor A. Ignatiev J.W. Rabalais 《Journal of Electron Spectroscopy and Related Phenomena》1978,14(2):143-153
A source and differential pumping system for producing high intensity resonance line radiation from rare gas atoms and ions for ultrahigh vacuum (UHV) photoelectron spectroscopy has been developed. Photoelectron count rates from a gold sample, as measured with a double-pass cylindrical mirror analyzer at pass energy 15 eV and 0.10 eV resolution, are ~ 300,000 c s?1 for the He(I) (21.22 eV) line and ~30000 c s?1 for the He(II) (40.81 eV) line. The source design is based on the principle of the electrostatic charged particle oscillator and is capable of sustaining discharges over the pressure range 1 to ~ 10?6 torr. The discharge segment consists of a cylindrical cold cathode surrounding two tungsten rod anodes which are held at high positive potential. Three stages of differential pumping are employed in order that the vacuum in the main spectrometer chamber can be maintained at 2 × 10?10 torr during operation. The calculated helium flow reaching the main chamber under these conditions is < 101 s?1. Details of the construction and operating characteristics of the source are presented. 相似文献
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We present a design for a spin-exchange optical pumping system to produce large quantities of highly polarized 129Xe. Low xenon concentrations in the flowing gas mixture allow the laser to maintain high Rb polarization. The large spin-exchange rate between Rb and 129Xe through the long-lived van der Waals molecules at low pressure, combined with a high flow rate, results in large production rates of hyperpolarized xenon. We report a maximum polarization of 64% achieved for a 0.3 l/h Xe flow rate, and maximum magnetization output of 6 l/h at 22% polarization. Our findings regarding the polarization dependence on temperature, nitrogen partial pressure, and gas mixture flow velocity are also reported. 相似文献
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Rui Chang Young Pyo Hong Stephanus Axnanda Baohua Mao Naila Jabeen Suidong Wang Renzhong Tai Zhi Liu 《Current Applied Physics》2012,12(5):1292-1296
We report Ambient pressure X-ray Photoelectron Spectroscopy Endstation with an integrated chemical analytical system that consists of a residual gas analyzer in the 2nd differential pumping stage and a new low-reactive sample holder heating assembly. This system has a linear response to the reaction chamber gas pressure. The sample heating assembly also has a low dark reaction rate up to 400 °C for H2 and CO oxidation. We expect this chemical analytical system will expand our capabilities in conducting in-operando catalysis research. 相似文献
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Argon was excited by intense electron beam pumping. The optical gain obtainable in Ar
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at 126 nm was investigated as a function of gas pressure and pumping density. The gas pressure necessary to achieve a gain of 10%/cm is reduced from 3.2 to 1.0 MPa if the gas is cooled at 170 K. The effect is partly due to reduced absorption by the removal of impurities. The results allow one a new approach to construct high-power lasers in the vacuum ultraviolet below 150 nm. 相似文献
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介绍了EAST真空室内巡视系统(IVVS)系统对EAST真空室第一壁进行巡检操作的工作原理,并基于系统部分材料出气率测试对其真空性能进行了分析.获得了在有效抽速为1064L·s–1的条件下,IVVS系统试验样机所采用的真空容器的极限真空度为3.37×10–3Pa.为优化IVVS真空性能,结合材料放气率试验,将部分材料更换为放气率低的材料,对系统进行烘烤处理,并对其中的相关结构提出了优化方案.优化后系统的真空性能有明显提高,在同等抽速条件下的极限真空度在1×10–4Pa范围内,能够满足EAST接受的真空环境要求.此外,抽气机组增添低温泵可以更进一步提高系统的真空性能. 相似文献
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介绍了EAST真空室内巡视系统(IVVS)系统对EAST真空室第一壁进行巡检操作的工作原理,并基于系统部分材料出气率测试对其真空性能进行了分析。获得了在有效抽速为1064L•s–1的条件下,IVVS系统试验样机所采用的真空容器的极限真空度为3.37×10–3Pa。为优化IVVS真空性能,结合材料放气率试验,将部分材料更换为放气率低的材料,对系统进行烘烤处理,并对其中的相关结构提出了优化方案。优化后系统的真空性能有明显提高,在同等抽速条件下的极限真空度在1×10–4Pa范围内,能够满足EAST接受的真空环境要求。此外,抽气机组增添低温泵可以更进一步提高系统的真空性能。 相似文献
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A three-level ∧-model atomic system with incoherent pumping is proposed to achieve high refractive index without absorption. In this kind of model, two lower levels are near-degenerate levels. It is found that high refractive index accompanied by vanishing absorption can be always accomplished by adjusting some related parameters. Although probe field is very weak, the SGC effect is prominent in the presence of incoherent pumping. 相似文献
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谐振式压力微传感器因其高精度、高稳定性及准数字输出等特性而广泛应用于气压监测、航空航天等领域。相较于其他结构,差分谐振式具有灵敏度高、线性度好及温度漂移小等优势。然而,要获得差分谐振式压力微传感器的最优性能,仍需解决差分谐振梁灵敏度不匹配的问题。在仿真与实验的基础上,对差分谐振式压力微传感器的灵敏度匹配特性进行了相关研究。根据研究结果,对传感器的结构参数进行了优化设计。两谐振梁的设计灵敏度为46 Hz/kP,实验结果显示中心梁的实际灵敏度为45 Hz/kPa,边梁的实际灵敏度为-44 Hz/kPa,差分输出的线性度高达0.999 999 9。 相似文献