ABSTRACT

A novel variation of the Langmuir probe for spatially resolved ion density measurements in a dense flowing plasma is presented. The technique uses a spinning disc to rapidly transit a wire probe through the flame. Spatial resolution is accomplished by post-processing data collected with many wire locations. The technique resolves ion density with a resolution of 0.5 mm in a 3000 K atmospheric pressure flame. The oxyfuel cutting torch flame under study is found to have twelve hollow cones with a 1 mm base and 4 mm height with ion density $3\times {10}^{18}$m${ }^{-3}$ along their surface. The base of the cones forms a ring, the inner diameter of which exhibits similarly large ion density, while the outer diameter appears to be weakened by entrained air. The ion densities decay over mm length scales from their peaks in the inner cones to form a semi-homogeneous annulus with ion density on the order $1\times {10}^{17}$m${ }^{-3}$.

摘要

提出了一种用于在稠密流动等离子体中进行空间分辨离子密度测量的 Langmuir 探针的新变体。该技术使用旋转圆盘快速将线探针穿过火焰。空间分辨率是通过对从许多电线位置收集的数据进行后处理来实现的。该技术在 3000 K 大气压火焰中以 0.5 mm 的分辨率解析离子密度。研究中的氧燃料割炬火焰被发现有十二个空心锥体，底部为 1 毫米，高度为 4 毫米，离子密度$3\times {10}^{18}$米${ }^{-3}$沿着它们的表面。锥体的底部形成一个环，其内径表现出同样大的离子密度，而外径似乎被夹带的空气削弱。离子密度从它们在内锥中的峰值在毫米长度尺度上衰减，形成一个离子密度在数量级上的半均匀环$1\times {10}^{17}$米${ }^{-3}$.