Space-Resolved Measurement of Cryogenic Plasma Produced by Pulsed Discharges in Superfluid Liquid Helium

超流液氦中脉冲放电产生的低温等离子体的空间分辨测量

• 批准号: 10680453
• 负责人: MINAMI Kazuo
• 金额: $ 2.18万
• 依托单位: NIIGATA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10680453/
• 关键词: Liquid Helium; Cryogenic Plasma; Ion Superfluidity; Stark Broadening; Spectroscopy; Spatial Resorution; Pulsed Discharge; Needle Electrode

In the term of 1998 and 1999, time and space resolved measurements were carried out to observe the density of afterglow plasma produced by pulsed discharges between needle electrodes immersed in superfluid liquid helium. The Stark broadening of spectral line 587.6 nm emanated from neutral helium atoms surrounded by plasma is observed to deduce local plasma density. Tungsten electrodes with tip curvature 50 micrometers for beam source in electron microscopes are used, and we find that reproducibility of the pulsed discharges is much improved than before. The electrode separation is 0.3 mm, and high voltage pulses of 20 kV, current 50 A and time width 1 micro-sec are applied to the electrodes. In order to accomplish spatial resolution, we bought and prepared an optical bench that enabled us to move the collimating lens for the slit of spectrometer with 0.1 mm resolution precisely in three-dimensional directions. The maximum light intensity of spectral line is obtained, when the focal image of the light source is created on the slit. Let us assume three-dimensional Cartesian coordinates ; x-axis is towards the slit from light source, z-axis is upward the light spot. The most sensitive change in plasma density is observed in y-direction. The density changes to a half value, when the displacement is 0.2 mm. In z-direction, on the other hand, the half value of the density is obtained for the displacement of 0.8 mm. The plasma is estimated to be a shape of an flat ellipsoid with rotational axis identical to the shank of the electrodes. In conclusion, we are going to clarify the spatial structure of the localized cryogenic plasma in liquid helium that is observed first in the world. Further efforts will be continued to attain detailed information.

在1998年和1999年期间，进行了时间和空间分辨的测量，以观察浸入超级流体液体氦气中的针料之间的脉冲放电产生的余辉等离子体的密度。观察到从被血浆包围的中性氦原子发出的光谱线587.6 nm的鲜明拓宽可推断局部血浆密度。使用电子显微镜中的梁源的尖端曲率50微米的钨电极，我们发现脉冲放电的可重复性比以前有所提高。电极分离为0.3毫米，高压脉冲为20 kV，电流50 A和时间宽度1 micro-SEC用于电极。为了实现空间分辨率，我们购买并准备了一个光学台，使我们能够以0.1 mm分辨率的光谱仪的缝隙移动准准透镜，恰好是三维方向。当在狭缝上创建光源的焦点图像时，获得光谱线的最大光强度。让我们假设三维笛卡尔坐标； X轴朝着光源的缝隙，Z轴向上向上亮点。在Y方向上观察到血浆密度最敏感的变化。当位移为0.2 mm时，密度变为一半。另一方面，在z方向上，将获得0.8 mm的位移的密度的一半。血浆估计是平坦的椭圆形的形状，其旋转轴与电极的小腿相同。总之，我们将阐明液态氦中局部低温血浆的空间结构，这首先在世界上观察到。将继续进一步的努力来获得详细的信息。