首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Two Dimensional Imaging of the Virtual Source of a Supersonic Beam: Helium at 125 K
【24h】

Two Dimensional Imaging of the Virtual Source of a Supersonic Beam: Helium at 125 K

机译:超声束虚拟源的二维成像:125 K氦气

获取原文
获取原文并翻译 | 示例
           

摘要

Here we present the first two-dimensional images of the virtual source of a supersonic helium expansion. The images were obtained using a free-standing Fresnel zone plate with an outermost zone width of 50 nm as imaging lens and a beam cooled to around 125 K. The nozzle diameter was 10 μm. The virtual source diameter was found to increase with stagnation pressure from 140 ± 30 μm at p_o = 21 bar up to 270 ± 25 μm at p_o = 101 bar. The experimental results are compared to a theoretical model based on the solution of the Boltzmann equation by the method of moments. The quantum mechanical cross sections used in the model have been calculated for the Lennard-Jones (LJ) and the Hurly-Moldover (HM) p_otentials. By using a scaling of the perpendicular temperature that parametrizes the perpendicular velocity distribution based on a continuum expansion approach, the LJ p_otential shows a good overall agreement with the experiment. However, at higher pressures the data p_oints lie in between the two theoretical curves and the slope of the trend is more similar to the HM curve. Real gas corrections to enthalpy are considered but they affect the results less than the experimental errors.
机译:在这里,我们介绍超声速氦气膨胀的虚拟源的第一个二维图像。使用具有最外层宽度为50 nm的自立式菲涅耳波带片作为成像透镜和冷却至约125 K的光束获得图像。喷嘴直径为10μm。发现虚拟源直径随停滞压力而增加,从p_o = 21 bar时的140±30μm增大到p_o = 101 bar时的270±25μm。将实验结果与基于矩法的玻尔兹曼方程解的理论模型进行了比较。该模型中使用的量子力学截面已针对Lennard-Jones(LJ)和Hurly-Moldover(HM)势进行了计算。通过使用基于连续扩展方法对垂直速度分布进行参数化的垂直温度比例,LJ势能与实验显示出良好的整体一致性。但是,在较高压力下,数据p_oints位于两条理论曲线之间,并且趋势的斜率更类似于HM曲线。考虑了对焓的实际气体校正,但它们对结果的影响小于实验误差。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱:kefu@zhangqiaokeyan.com

京公网安备:11010802029741号 ICP备案号:京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有
  • 客服微信

  • 服务号